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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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/*
 * (C) Copyright Taligent, Inc. 1996-1998 - All Rights Reserved
 * (C) Copyright IBM Corp. 1996-1998 - All Rights Reserved
 *
 *   The original version of this source code and documentation is copyrighted
 * and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
 * materials are provided under terms of a License Agreement between Taligent
 * and Sun. This technology is protected by multiple US and International
 * patents. This notice and attribution to Taligent may not be removed.
 *   Taligent is a registered trademark of Taligent, Inc.
 *
 */

package java.util;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OptionalDataException;
import java.io.Serializable;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PermissionCollection;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.security.ProtectionDomain;
import java.text.DateFormat;
import java.text.DateFormatSymbols;
import java.time.Instant;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import sun.util.BuddhistCalendar;
import sun.util.calendar.ZoneInfo;
import sun.util.locale.provider.CalendarDataUtility;
import sun.util.locale.provider.LocaleProviderAdapter;
import sun.util.locale.provider.TimeZoneNameUtility;
import sun.util.spi.CalendarProvider;


The Calendar class is an abstract class that provides methods for converting between a specific instant in time and a set of calendar fields such as YEAR, MONTH,
DAY_OF_MONTH, HOUR, and so on, and for
manipulating the calendar fields, such as getting the date of the next
week. An instant in time can be represented by a millisecond value that is
an offset from the Epoch, January 1, 1970
00:00:00.000 GMT (Gregorian).

The class also provides additional fields and methods for
implementing a concrete calendar system outside the package. Those
fields and methods are defined as protected.


Like other locale-sensitive classes, Calendar provides a
class method, getInstance, for getting a generally useful
object of this type. Calendar's getInstance method
returns a Calendar object whose
calendar fields have been initialized with the current date and time:



    Calendar rightNow = Calendar.getInstance();





A Calendar object can produce all the calendar field values
needed to implement the date-time formatting for a particular language and
calendar style (for example, Japanese-Gregorian, Japanese-Traditional).
Calendar defines the range of values returned by
certain calendar fields, as well as their meaning.  For example,
the first month of the calendar system has value MONTH ==
JANUARY for all calendars.  Other values are defined by the
concrete subclass, such as ERA.  See individual field
documentation and subclass documentation for details.

Getting and Setting Calendar Field Values


The calendar field values can be set by calling the set
methods. Any field values set in a Calendar will not be
interpreted until it needs to calculate its time value (milliseconds from
the Epoch) or values of the calendar fields. Calling the
get, getTimeInMillis, getTime,
add and roll involves such calculation.

Leniency


Calendar has two modes for interpreting the calendar
fields, lenient and non-lenient.  When a
Calendar is in lenient mode, it accepts a wider range of
calendar field values than it produces.  When a Calendar
recomputes calendar field values for return by get(), all of
the calendar fields are normalized. For example, a lenient
GregorianCalendar interprets MONTH == JANUARY,
DAY_OF_MONTH == 32 as February 1.

When a Calendar is in non-lenient mode, it throws an
exception if there is any inconsistency in its calendar fields. For
example, a GregorianCalendar always produces
DAY_OF_MONTH values between 1 and the length of the month. A
non-lenient GregorianCalendar throws an exception upon
calculating its time or calendar field values if any out-of-range field
value has been set.

First Week

Calendar defines a locale-specific seven day week using two parameters: the first day of the week and the minimal days in first week (from 1 to 7). These numbers are taken from the locale resource data or the locale itself when a Calendar is constructed. If the designated locale contains "fw" and/or "rg" 
Unicode extensions, the first day of the week will be obtained according to
those extensions. If both "fw" and "rg" are specified, the value from the "fw"
extension supersedes the implicit one from the "rg" extension.
They may also be specified explicitly through the methods for setting their
values.

When setting or getting the WEEK_OF_MONTH or
WEEK_OF_YEAR fields, Calendar must determine the
first week of the month or year as a reference point.  The first week of a
month or year is defined as the earliest seven day period beginning on
getFirstDayOfWeek() and containing at least
getMinimalDaysInFirstWeek() days of that month or year.  Weeks
numbered ..., -1, 0 precede the first week; weeks numbered 2, 3,... follow
it.  Note that the normalized numbering returned by get() may be
different.  For example, a specific Calendar subclass may
designate the week before week 1 of a year as week n of
the previous year.

Calendar Fields Resolution

When computing a date and time from the calendar fields, there
may be insufficient information for the computation (such as only
year and month with no day of month), or there may be inconsistent
information (such as Tuesday, July 15, 1996 (Gregorian) -- July 15,
1996 is actually a Monday). Calendar will resolve
calendar field values to determine the date and time in the
following way.

If there is any conflict in calendar field values,
Calendar gives priorities to calendar fields that have been set
more recently. The following are the default combinations of the
calendar fields. The most recent combination, as determined by the
most recently set single field, will be used.

For the date fields:



YEAR + MONTH + DAY_OF_MONTH
YEAR + MONTH + WEEK_OF_MONTH + DAY_OF_WEEK
YEAR + MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK
YEAR + DAY_OF_YEAR
YEAR + DAY_OF_WEEK + WEEK_OF_YEAR


For the time of day fields:



HOUR_OF_DAY
AM_PM + HOUR



If there are any calendar fields whose values haven't been set in the selected
field combination, Calendar uses their default values. The default
value of each field may vary by concrete calendar systems. For example, in
GregorianCalendar, the default of a field is the same as that
of the start of the Epoch: i.e., YEAR = 1970, MONTH =
JANUARY, DAY_OF_MONTH = 1, etc.


Note: There are certain possible ambiguities in
interpretation of certain singular times, which are resolved in the
following ways:

    
    
  1.  23:59 is the last minute of the day and 00:00 is the first
         minute of the next day. Thus, 23:59 on Dec 31, 1999 < 00:00 on
         Jan 1, 2000 < 00:01 on Jan 1, 2000.
    
  2.  Although historically not precise, midnight also belongs to "am",
         and noon belongs to "pm", so on the same day,
         12:00 am (midnight) < 12:01 am, and 12:00 pm (noon) < 12:01 pm



 The date or time format strings are not part of the definition of a calendar, as those must be modifiable or overridable by the user at runtime. Use DateFormat to format dates. 
Field Manipulation

The calendar fields can be changed using three methods:
set(), add(), and roll().

set(f, value) changes calendar field
f to value.  In addition, it sets an
internal member variable to indicate that calendar field f has
been changed. Although calendar field f is changed immediately,
the calendar's time value in milliseconds is not recomputed until the next call to
get(), getTime(), getTimeInMillis(),
add(), or roll() is made. Thus, multiple calls to
set() do not trigger multiple, unnecessary
computations. As a result of changing a calendar field using
set(), other calendar fields may also change, depending on the
calendar field, the calendar field value, and the calendar system. In addition,
get(f) will not necessarily return value set by
the call to the set method
after the calendar fields have been recomputed. The specifics are determined by
the concrete calendar class.


Example: Consider a GregorianCalendar
originally set to August 31, 1999. Calling set(Calendar.MONTH,
Calendar.SEPTEMBER) sets the date to September 31,
1999. This is a temporary internal representation that resolves to
October 1, 1999 if getTime()is then called. However, a
call to set(Calendar.DAY_OF_MONTH, 30) before the call to
getTime() sets the date to September 30, 1999, since
no recomputation occurs after set() itself.


add(f, delta) adds delta
to field f.  This is equivalent to calling set(f,
get(f) + delta) with two adjustments:



  
Add rule 1. The value of field f
  after the call minus the value of field f before the
  call is delta, modulo any overflow that has occurred in
  field f. Overflow occurs when a field value exceeds its
  range and, as a result, the next larger field is incremented or
  decremented and the field value is adjusted back into its range.

  
Add rule 2. If a smaller field is expected to be
  invariant, but it is impossible for it to be equal to its
  prior value because of changes in its minimum or maximum after field
  f is changed or other constraints, such as time zone
  offset changes, then its value is adjusted to be as close
  as possible to its expected value. A smaller field represents a
  smaller unit of time. HOUR is a smaller field than
  DAY_OF_MONTH. No adjustment is made to smaller fields
  that are not expected to be invariant. The calendar system
  determines what fields are expected to be invariant.




In addition, unlike set(), add() forces
an immediate recomputation of the calendar's milliseconds and all
fields.


Example: Consider a GregorianCalendar
originally set to August 31, 1999. Calling add(Calendar.MONTH,
13) sets the calendar to September 30, 2000. Add rule
1 sets the MONTH field to September, since
adding 13 months to August gives September of the next year. Since
DAY_OF_MONTH cannot be 31 in September in a
GregorianCalendar, add rule 2 sets the
DAY_OF_MONTH to 30, the closest possible value. Although
it is a smaller field, DAY_OF_WEEK is not adjusted by
rule 2, since it is expected to change when the month changes in a
GregorianCalendar.


roll(f, delta) adds
delta to field f without changing larger
fields. This is equivalent to calling add(f, delta) with
the following adjustment:



  
Roll rule. Larger fields are unchanged after the
  call. A larger field represents a larger unit of
  time. DAY_OF_MONTH is a larger field than
  HOUR.




Example: See GregorianCalendar.roll(int, int). 
Usage model. To motivate the behavior of
add() and roll(), consider a user interface
component with increment and decrement buttons for the month, day, and
year, and an underlying GregorianCalendar. If the
interface reads January 31, 1999 and the user presses the month
increment button, what should it read? If the underlying
implementation uses set(), it might read March 3, 1999. A
better result would be February 28, 1999. Furthermore, if the user
presses the month increment button again, it should read March 31,
1999, not March 28, 1999. By saving the original date and using either
add() or roll(), depending on whether larger
fields should be affected, the user interface can behave as most users
will intuitively expect.


Author:Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu
See Also:
Since:1.1
/**
 * The <code>Calendar</code> class is an abstract class that provides methods
 * for converting between a specific instant in time and a set of {@link
 * #fields calendar fields} such as <code>YEAR</code>, <code>MONTH</code>,
 * <code>DAY_OF_MONTH</code>, <code>HOUR</code>, and so on, and for
 * manipulating the calendar fields, such as getting the date of the next
 * week. An instant in time can be represented by a millisecond value that is
 * an offset from the <a id="Epoch"><em>Epoch</em></a>, January 1, 1970
 * 00:00:00.000 GMT (Gregorian).
 *
 * <p>The class also provides additional fields and methods for
 * implementing a concrete calendar system outside the package. Those
 * fields and methods are defined as <code>protected</code>.
 *
 * <p>
 * Like other locale-sensitive classes, <code>Calendar</code> provides a
 * class method, <code>getInstance</code>, for getting a generally useful
 * object of this type. <code>Calendar</code>'s <code>getInstance</code> method
 * returns a <code>Calendar</code> object whose
 * calendar fields have been initialized with the current date and time:
 * <blockquote>
 * <pre>
 *     Calendar rightNow = Calendar.getInstance();
 * </pre>
 * </blockquote>
 *
 * <p>A <code>Calendar</code> object can produce all the calendar field values
 * needed to implement the date-time formatting for a particular language and
 * calendar style (for example, Japanese-Gregorian, Japanese-Traditional).
 * <code>Calendar</code> defines the range of values returned by
 * certain calendar fields, as well as their meaning.  For example,
 * the first month of the calendar system has value <code>MONTH ==
 * JANUARY</code> for all calendars.  Other values are defined by the
 * concrete subclass, such as <code>ERA</code>.  See individual field
 * documentation and subclass documentation for details.
 *
 * <h3>Getting and Setting Calendar Field Values</h3>
 *
 * <p>The calendar field values can be set by calling the <code>set</code>
 * methods. Any field values set in a <code>Calendar</code> will not be
 * interpreted until it needs to calculate its time value (milliseconds from
 * the Epoch) or values of the calendar fields. Calling the
 * <code>get</code>, <code>getTimeInMillis</code>, <code>getTime</code>,
 * <code>add</code> and <code>roll</code> involves such calculation.
 *
 * <h4>Leniency</h4>
 *
 * <p><code>Calendar</code> has two modes for interpreting the calendar
 * fields, <em>lenient</em> and <em>non-lenient</em>.  When a
 * <code>Calendar</code> is in lenient mode, it accepts a wider range of
 * calendar field values than it produces.  When a <code>Calendar</code>
 * recomputes calendar field values for return by <code>get()</code>, all of
 * the calendar fields are normalized. For example, a lenient
 * <code>GregorianCalendar</code> interprets <code>MONTH == JANUARY</code>,
 * <code>DAY_OF_MONTH == 32</code> as February 1.

 * <p>When a <code>Calendar</code> is in non-lenient mode, it throws an
 * exception if there is any inconsistency in its calendar fields. For
 * example, a <code>GregorianCalendar</code> always produces
 * <code>DAY_OF_MONTH</code> values between 1 and the length of the month. A
 * non-lenient <code>GregorianCalendar</code> throws an exception upon
 * calculating its time or calendar field values if any out-of-range field
 * value has been set.
 *
 * <h4><a id="first_week">First Week</a></h4>
 *
 * <code>Calendar</code> defines a locale-specific seven day week using two
 * parameters: the first day of the week and the minimal days in first week
 * (from 1 to 7).  These numbers are taken from the locale resource data or the
 * locale itself when a {@code Calendar} is constructed. If the designated
 * locale contains "fw" and/or "rg" <a href="./Locale.html#def_locale_extension">
 * Unicode extensions</a>, the first day of the week will be obtained according to
 * those extensions. If both "fw" and "rg" are specified, the value from the "fw"
 * extension supersedes the implicit one from the "rg" extension.
 * They may also be specified explicitly through the methods for setting their
 * values.
 *
 * <p>When setting or getting the <code>WEEK_OF_MONTH</code> or
 * <code>WEEK_OF_YEAR</code> fields, <code>Calendar</code> must determine the
 * first week of the month or year as a reference point.  The first week of a
 * month or year is defined as the earliest seven day period beginning on
 * <code>getFirstDayOfWeek()</code> and containing at least
 * <code>getMinimalDaysInFirstWeek()</code> days of that month or year.  Weeks
 * numbered ..., -1, 0 precede the first week; weeks numbered 2, 3,... follow
 * it.  Note that the normalized numbering returned by <code>get()</code> may be
 * different.  For example, a specific <code>Calendar</code> subclass may
 * designate the week before week 1 of a year as week <code><i>n</i></code> of
 * the previous year.
 *
 * <h4>Calendar Fields Resolution</h4>
 *
 * When computing a date and time from the calendar fields, there
 * may be insufficient information for the computation (such as only
 * year and month with no day of month), or there may be inconsistent
 * information (such as Tuesday, July 15, 1996 (Gregorian) -- July 15,
 * 1996 is actually a Monday). <code>Calendar</code> will resolve
 * calendar field values to determine the date and time in the
 * following way.
 *
 * <p><a id="resolution">If there is any conflict in calendar field values,
 * <code>Calendar</code> gives priorities to calendar fields that have been set
 * more recently.</a> The following are the default combinations of the
 * calendar fields. The most recent combination, as determined by the
 * most recently set single field, will be used.
 *
 * <p><a id="date_resolution">For the date fields</a>:
 * <blockquote>
 * <pre>
 * YEAR + MONTH + DAY_OF_MONTH
 * YEAR + MONTH + WEEK_OF_MONTH + DAY_OF_WEEK
 * YEAR + MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK
 * YEAR + DAY_OF_YEAR
 * YEAR + DAY_OF_WEEK + WEEK_OF_YEAR
 * </pre></blockquote>
 *
 * <a id="time_resolution">For the time of day fields</a>:
 * <blockquote>
 * <pre>
 * HOUR_OF_DAY
 * AM_PM + HOUR
 * </pre></blockquote>
 *
 * <p>If there are any calendar fields whose values haven't been set in the selected
 * field combination, <code>Calendar</code> uses their default values. The default
 * value of each field may vary by concrete calendar systems. For example, in
 * <code>GregorianCalendar</code>, the default of a field is the same as that
 * of the start of the Epoch: i.e., <code>YEAR = 1970</code>, <code>MONTH =
 * JANUARY</code>, <code>DAY_OF_MONTH = 1</code>, etc.
 *
 * <p>
 * <strong>Note:</strong> There are certain possible ambiguities in
 * interpretation of certain singular times, which are resolved in the
 * following ways:
 * <ol>
 *     <li> 23:59 is the last minute of the day and 00:00 is the first
 *          minute of the next day. Thus, 23:59 on Dec 31, 1999 &lt; 00:00 on
 *          Jan 1, 2000 &lt; 00:01 on Jan 1, 2000.
 *
 *     <li> Although historically not precise, midnight also belongs to "am",
 *          and noon belongs to "pm", so on the same day,
 *          12:00 am (midnight) &lt; 12:01 am, and 12:00 pm (noon) &lt; 12:01 pm
 * </ol>
 *
 * <p>
 * The date or time format strings are not part of the definition of a
 * calendar, as those must be modifiable or overridable by the user at
 * runtime. Use {@link DateFormat}
 * to format dates.
 *
 * <h4>Field Manipulation</h4>
 *
 * The calendar fields can be changed using three methods:
 * <code>set()</code>, <code>add()</code>, and <code>roll()</code>.
 *
 * <p><strong><code>set(f, value)</code></strong> changes calendar field
 * <code>f</code> to <code>value</code>.  In addition, it sets an
 * internal member variable to indicate that calendar field <code>f</code> has
 * been changed. Although calendar field <code>f</code> is changed immediately,
 * the calendar's time value in milliseconds is not recomputed until the next call to
 * <code>get()</code>, <code>getTime()</code>, <code>getTimeInMillis()</code>,
 * <code>add()</code>, or <code>roll()</code> is made. Thus, multiple calls to
 * <code>set()</code> do not trigger multiple, unnecessary
 * computations. As a result of changing a calendar field using
 * <code>set()</code>, other calendar fields may also change, depending on the
 * calendar field, the calendar field value, and the calendar system. In addition,
 * <code>get(f)</code> will not necessarily return <code>value</code> set by
 * the call to the <code>set</code> method
 * after the calendar fields have been recomputed. The specifics are determined by
 * the concrete calendar class.</p>
 *
 * <p><em>Example</em>: Consider a <code>GregorianCalendar</code>
 * originally set to August 31, 1999. Calling <code>set(Calendar.MONTH,
 * Calendar.SEPTEMBER)</code> sets the date to September 31,
 * 1999. This is a temporary internal representation that resolves to
 * October 1, 1999 if <code>getTime()</code>is then called. However, a
 * call to <code>set(Calendar.DAY_OF_MONTH, 30)</code> before the call to
 * <code>getTime()</code> sets the date to September 30, 1999, since
 * no recomputation occurs after <code>set()</code> itself.</p>
 *
 * <p><strong><code>add(f, delta)</code></strong> adds <code>delta</code>
 * to field <code>f</code>.  This is equivalent to calling <code>set(f,
 * get(f) + delta)</code> with two adjustments:</p>
 *
 * <blockquote>
 *   <p><strong>Add rule 1</strong>. The value of field <code>f</code>
 *   after the call minus the value of field <code>f</code> before the
 *   call is <code>delta</code>, modulo any overflow that has occurred in
 *   field <code>f</code>. Overflow occurs when a field value exceeds its
 *   range and, as a result, the next larger field is incremented or
 *   decremented and the field value is adjusted back into its range.</p>
 *
 *   <p><strong>Add rule 2</strong>. If a smaller field is expected to be
 *   invariant, but it is impossible for it to be equal to its
 *   prior value because of changes in its minimum or maximum after field
 *   <code>f</code> is changed or other constraints, such as time zone
 *   offset changes, then its value is adjusted to be as close
 *   as possible to its expected value. A smaller field represents a
 *   smaller unit of time. <code>HOUR</code> is a smaller field than
 *   <code>DAY_OF_MONTH</code>. No adjustment is made to smaller fields
 *   that are not expected to be invariant. The calendar system
 *   determines what fields are expected to be invariant.</p>
 * </blockquote>
 *
 * <p>In addition, unlike <code>set()</code>, <code>add()</code> forces
 * an immediate recomputation of the calendar's milliseconds and all
 * fields.</p>
 *
 * <p><em>Example</em>: Consider a <code>GregorianCalendar</code>
 * originally set to August 31, 1999. Calling <code>add(Calendar.MONTH,
 * 13)</code> sets the calendar to September 30, 2000. <strong>Add rule
 * 1</strong> sets the <code>MONTH</code> field to September, since
 * adding 13 months to August gives September of the next year. Since
 * <code>DAY_OF_MONTH</code> cannot be 31 in September in a
 * <code>GregorianCalendar</code>, <strong>add rule 2</strong> sets the
 * <code>DAY_OF_MONTH</code> to 30, the closest possible value. Although
 * it is a smaller field, <code>DAY_OF_WEEK</code> is not adjusted by
 * rule 2, since it is expected to change when the month changes in a
 * <code>GregorianCalendar</code>.</p>
 *
 * <p><strong><code>roll(f, delta)</code></strong> adds
 * <code>delta</code> to field <code>f</code> without changing larger
 * fields. This is equivalent to calling <code>add(f, delta)</code> with
 * the following adjustment:</p>
 *
 * <blockquote>
 *   <p><strong>Roll rule</strong>. Larger fields are unchanged after the
 *   call. A larger field represents a larger unit of
 *   time. <code>DAY_OF_MONTH</code> is a larger field than
 *   <code>HOUR</code>.</p>
 * </blockquote>
 *
 * <p><em>Example</em>: See {@link java.util.GregorianCalendar#roll(int, int)}.
 *
 * <p><strong>Usage model</strong>. To motivate the behavior of
 * <code>add()</code> and <code>roll()</code>, consider a user interface
 * component with increment and decrement buttons for the month, day, and
 * year, and an underlying <code>GregorianCalendar</code>. If the
 * interface reads January 31, 1999 and the user presses the month
 * increment button, what should it read? If the underlying
 * implementation uses <code>set()</code>, it might read March 3, 1999. A
 * better result would be February 28, 1999. Furthermore, if the user
 * presses the month increment button again, it should read March 31,
 * 1999, not March 28, 1999. By saving the original date and using either
 * <code>add()</code> or <code>roll()</code>, depending on whether larger
 * fields should be affected, the user interface can behave as most users
 * will intuitively expect.</p>
 *
 * @see          java.lang.System#currentTimeMillis()
 * @see          Date
 * @see          GregorianCalendar
 * @see          TimeZone
 * @see          java.text.DateFormat
 * @author Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu
 * @since 1.1
 */
public abstract class Calendar implements Serializable, Cloneable, Comparable<Calendar> {

    // Data flow in Calendar
    // ---------------------

    // The current time is represented in two ways by Calendar: as UTC
    // milliseconds from the epoch (1 January 1970 0:00 UTC), and as local
    // fields such as MONTH, HOUR, AM_PM, etc.  It is possible to compute the
    // millis from the fields, and vice versa.  The data needed to do this
    // conversion is encapsulated by a TimeZone object owned by the Calendar.
    // The data provided by the TimeZone object may also be overridden if the
    // user sets the ZONE_OFFSET and/or DST_OFFSET fields directly. The class
    // keeps track of what information was most recently set by the caller, and
    // uses that to compute any other information as needed.

    // If the user sets the fields using set(), the data flow is as follows.
    // This is implemented by the Calendar subclass's computeTime() method.
    // During this process, certain fields may be ignored.  The disambiguation
    // algorithm for resolving which fields to pay attention to is described
    // in the class documentation.

    //   local fields (YEAR, MONTH, DATE, HOUR, MINUTE, etc.)
    //           |
    //           | Using Calendar-specific algorithm
    //           V
    //   local standard millis
    //           |
    //           | Using TimeZone or user-set ZONE_OFFSET / DST_OFFSET
    //           V
    //   UTC millis (in time data member)

    // If the user sets the UTC millis using setTime() or setTimeInMillis(),
    // the data flow is as follows.  This is implemented by the Calendar
    // subclass's computeFields() method.

    //   UTC millis (in time data member)
    //           |
    //           | Using TimeZone getOffset()
    //           V
    //   local standard millis
    //           |
    //           | Using Calendar-specific algorithm
    //           V
    //   local fields (YEAR, MONTH, DATE, HOUR, MINUTE, etc.)

    // In general, a round trip from fields, through local and UTC millis, and
    // back out to fields is made when necessary.  This is implemented by the
    // complete() method.  Resolving a partial set of fields into a UTC millis
    // value allows all remaining fields to be generated from that value.  If
    // the Calendar is lenient, the fields are also renormalized to standard
    // ranges when they are regenerated.

    
Field number for get and set indicating the
era, e.g., AD or BC in the Julian calendar. This is a calendar-specific
value; see subclass documentation.

See Also:
/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * era, e.g., AD or BC in the Julian calendar. This is a calendar-specific
     * value; see subclass documentation.
     *
     * @see GregorianCalendar#AD
     * @see GregorianCalendar#BC
     */
    public static final int ERA = 0;

    
Field number for get and set indicating the
year. This is a calendar-specific value; see subclass documentation.

/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * year. This is a calendar-specific value; see subclass documentation.
     */
    public static final int YEAR = 1;

    
Field number for get and set indicating the
month. This is a calendar-specific value. The first month of
the year in the Gregorian and Julian calendars is
JANUARY which is 0; the last depends on the number
of months in a year.

See Also:
/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * month. This is a calendar-specific value. The first month of
     * the year in the Gregorian and Julian calendars is
     * <code>JANUARY</code> which is 0; the last depends on the number
     * of months in a year.
     *
     * @see #JANUARY
     * @see #FEBRUARY
     * @see #MARCH
     * @see #APRIL
     * @see #MAY
     * @see #JUNE
     * @see #JULY
     * @see #AUGUST
     * @see #SEPTEMBER
     * @see #OCTOBER
     * @see #NOVEMBER
     * @see #DECEMBER
     * @see #UNDECIMBER
     */
    public static final int MONTH = 2;

    
Field number for get and set indicating the
week number within the current year.  The first week of the year, as
defined by getFirstDayOfWeek() and
getMinimalDaysInFirstWeek(), has value 1.  Subclasses define
the value of WEEK_OF_YEAR for days before the first week of
the year.

See Also:
/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * week number within the current year.  The first week of the year, as
     * defined by <code>getFirstDayOfWeek()</code> and
     * <code>getMinimalDaysInFirstWeek()</code>, has value 1.  Subclasses define
     * the value of <code>WEEK_OF_YEAR</code> for days before the first week of
     * the year.
     *
     * @see #getFirstDayOfWeek
     * @see #getMinimalDaysInFirstWeek
     */
    public static final int WEEK_OF_YEAR = 3;

    
Field number for get and set indicating the
week number within the current month.  The first week of the month, as
defined by getFirstDayOfWeek() and
getMinimalDaysInFirstWeek(), has value 1.  Subclasses define
the value of WEEK_OF_MONTH for days before the first week of
the month.

See Also:
/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * week number within the current month.  The first week of the month, as
     * defined by <code>getFirstDayOfWeek()</code> and
     * <code>getMinimalDaysInFirstWeek()</code>, has value 1.  Subclasses define
     * the value of <code>WEEK_OF_MONTH</code> for days before the first week of
     * the month.
     *
     * @see #getFirstDayOfWeek
     * @see #getMinimalDaysInFirstWeek
     */
    public static final int WEEK_OF_MONTH = 4;

    
Field number for get and set indicating the
day of the month. This is a synonym for DAY_OF_MONTH.
The first day of the month has value 1.

See Also:
  • DAY_OF_MONTH
/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * day of the month. This is a synonym for <code>DAY_OF_MONTH</code>.
     * The first day of the month has value 1.
     *
     * @see #DAY_OF_MONTH
     */
    public static final int DATE = 5;

    
Field number for get and set indicating the
day of the month. This is a synonym for DATE.
The first day of the month has value 1.

See Also:
  • DATE
/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * day of the month. This is a synonym for <code>DATE</code>.
     * The first day of the month has value 1.
     *
     * @see #DATE
     */
    public static final int DAY_OF_MONTH = 5;

    
Field number for get and set indicating the day
number within the current year.  The first day of the year has value 1.

/**
     * Field number for <code>get</code> and <code>set</code> indicating the day
     * number within the current year.  The first day of the year has value 1.
     */
    public static final int DAY_OF_YEAR = 6;

    
Field number for get and set indicating the day
of the week.  This field takes values SUNDAY,
MONDAY, TUESDAY, WEDNESDAY,
THURSDAY, FRIDAY, and SATURDAY.

See Also:
/**
     * Field number for <code>get</code> and <code>set</code> indicating the day
     * of the week.  This field takes values <code>SUNDAY</code>,
     * <code>MONDAY</code>, <code>TUESDAY</code>, <code>WEDNESDAY</code>,
     * <code>THURSDAY</code>, <code>FRIDAY</code>, and <code>SATURDAY</code>.
     *
     * @see #SUNDAY
     * @see #MONDAY
     * @see #TUESDAY
     * @see #WEDNESDAY
     * @see #THURSDAY
     * @see #FRIDAY
     * @see #SATURDAY
     */
    public static final int DAY_OF_WEEK = 7;

    
Field number for get and set indicating the
ordinal number of the day of the week within the current month. Together
with the DAY_OF_WEEK field, this uniquely specifies a day
within a month.  Unlike WEEK_OF_MONTH and
WEEK_OF_YEAR, this field's value does not depend on
getFirstDayOfWeek() or
getMinimalDaysInFirstWeek().  DAY_OF_MONTH 1
through 7 always correspond to DAY_OF_WEEK_IN_MONTH
1; 8 through 14 correspond to
DAY_OF_WEEK_IN_MONTH 2, and so on.
DAY_OF_WEEK_IN_MONTH 0 indicates the week before
DAY_OF_WEEK_IN_MONTH 1.  Negative values count back from the
end of the month, so the last Sunday of a month is specified as
DAY_OF_WEEK = SUNDAY, DAY_OF_WEEK_IN_MONTH = -1.  Because
negative values count backward they will usually be aligned differently
within the month than positive values.  For example, if a month has 31
days, DAY_OF_WEEK_IN_MONTH -1 will overlap
DAY_OF_WEEK_IN_MONTH 5 and the end of 4.

See Also:
/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * ordinal number of the day of the week within the current month. Together
     * with the <code>DAY_OF_WEEK</code> field, this uniquely specifies a day
     * within a month.  Unlike <code>WEEK_OF_MONTH</code> and
     * <code>WEEK_OF_YEAR</code>, this field's value does <em>not</em> depend on
     * <code>getFirstDayOfWeek()</code> or
     * <code>getMinimalDaysInFirstWeek()</code>.  <code>DAY_OF_MONTH 1</code>
     * through <code>7</code> always correspond to <code>DAY_OF_WEEK_IN_MONTH
     * 1</code>; <code>8</code> through <code>14</code> correspond to
     * <code>DAY_OF_WEEK_IN_MONTH 2</code>, and so on.
     * <code>DAY_OF_WEEK_IN_MONTH 0</code> indicates the week before
     * <code>DAY_OF_WEEK_IN_MONTH 1</code>.  Negative values count back from the
     * end of the month, so the last Sunday of a month is specified as
     * <code>DAY_OF_WEEK = SUNDAY, DAY_OF_WEEK_IN_MONTH = -1</code>.  Because
     * negative values count backward they will usually be aligned differently
     * within the month than positive values.  For example, if a month has 31
     * days, <code>DAY_OF_WEEK_IN_MONTH -1</code> will overlap
     * <code>DAY_OF_WEEK_IN_MONTH 5</code> and the end of <code>4</code>.
     *
     * @see #DAY_OF_WEEK
     * @see #WEEK_OF_MONTH
     */
    public static final int DAY_OF_WEEK_IN_MONTH = 8;

    
Field number for get and set indicating
whether the HOUR is before or after noon.
E.g., at 10:04:15.250 PM the AM_PM is PM.

See Also:
/**
     * Field number for <code>get</code> and <code>set</code> indicating
     * whether the <code>HOUR</code> is before or after noon.
     * E.g., at 10:04:15.250 PM the <code>AM_PM</code> is <code>PM</code>.
     *
     * @see #AM
     * @see #PM
     * @see #HOUR
     */
    public static final int AM_PM = 9;

    
Field number for get and set indicating the
hour of the morning or afternoon. HOUR is used for the
12-hour clock (0 - 11). Noon and midnight are represented by 0, not by 12.
E.g., at 10:04:15.250 PM the HOUR is 10.

See Also:
/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * hour of the morning or afternoon. <code>HOUR</code> is used for the
     * 12-hour clock (0 - 11). Noon and midnight are represented by 0, not by 12.
     * E.g., at 10:04:15.250 PM the <code>HOUR</code> is 10.
     *
     * @see #AM_PM
     * @see #HOUR_OF_DAY
     */
    public static final int HOUR = 10;

    
Field number for get and set indicating the
hour of the day. HOUR_OF_DAY is used for the 24-hour clock.
E.g., at 10:04:15.250 PM the HOUR_OF_DAY is 22.

See Also:
  • HOUR
/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * hour of the day. <code>HOUR_OF_DAY</code> is used for the 24-hour clock.
     * E.g., at 10:04:15.250 PM the <code>HOUR_OF_DAY</code> is 22.
     *
     * @see #HOUR
     */
    public static final int HOUR_OF_DAY = 11;

    
Field number for get and set indicating the
minute within the hour.
E.g., at 10:04:15.250 PM the MINUTE is 4.

/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * minute within the hour.
     * E.g., at 10:04:15.250 PM the <code>MINUTE</code> is 4.
     */
    public static final int MINUTE = 12;

    
Field number for get and set indicating the
second within the minute.
E.g., at 10:04:15.250 PM the SECOND is 15.

/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * second within the minute.
     * E.g., at 10:04:15.250 PM the <code>SECOND</code> is 15.
     */
    public static final int SECOND = 13;

    
Field number for get and set indicating the
millisecond within the second.
E.g., at 10:04:15.250 PM the MILLISECOND is 250.

/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * millisecond within the second.
     * E.g., at 10:04:15.250 PM the <code>MILLISECOND</code> is 250.
     */
    public static final int MILLISECOND = 14;

    
Field number for get and set
indicating the raw offset from GMT in milliseconds.


This field reflects the correct GMT offset value of the time
zone of this Calendar if the
TimeZone implementation subclass supports
historical GMT offset changes.

/**
     * Field number for <code>get</code> and <code>set</code>
     * indicating the raw offset from GMT in milliseconds.
     * <p>
     * This field reflects the correct GMT offset value of the time
     * zone of this <code>Calendar</code> if the
     * <code>TimeZone</code> implementation subclass supports
     * historical GMT offset changes.
     */
    public static final int ZONE_OFFSET = 15;

    
Field number for get and set indicating the
daylight saving offset in milliseconds.


This field reflects the correct daylight saving offset value of
the time zone of this Calendar if the
TimeZone implementation subclass supports
historical Daylight Saving Time schedule changes.

/**
     * Field number for <code>get</code> and <code>set</code> indicating the
     * daylight saving offset in milliseconds.
     * <p>
     * This field reflects the correct daylight saving offset value of
     * the time zone of this <code>Calendar</code> if the
     * <code>TimeZone</code> implementation subclass supports
     * historical Daylight Saving Time schedule changes.
     */
    public static final int DST_OFFSET = 16;

    
The number of distinct fields recognized by get and set.
Field numbers range from 0..FIELD_COUNT-1.

/**
     * The number of distinct fields recognized by <code>get</code> and <code>set</code>.
     * Field numbers range from <code>0..FIELD_COUNT-1</code>.
     */
    public static final int FIELD_COUNT = 17;

    
Value of the DAY_OF_WEEK field indicating Sunday. 
/**
     * Value of the {@link #DAY_OF_WEEK} field indicating
     * Sunday.
     */
    public static final int SUNDAY = 1;

    
Value of the DAY_OF_WEEK field indicating Monday. 
/**
     * Value of the {@link #DAY_OF_WEEK} field indicating
     * Monday.
     */
    public static final int MONDAY = 2;

    
Value of the DAY_OF_WEEK field indicating Tuesday. 
/**
     * Value of the {@link #DAY_OF_WEEK} field indicating
     * Tuesday.
     */
    public static final int TUESDAY = 3;

    
Value of the DAY_OF_WEEK field indicating Wednesday. 
/**
     * Value of the {@link #DAY_OF_WEEK} field indicating
     * Wednesday.
     */
    public static final int WEDNESDAY = 4;

    
Value of the DAY_OF_WEEK field indicating Thursday. 
/**
     * Value of the {@link #DAY_OF_WEEK} field indicating
     * Thursday.
     */
    public static final int THURSDAY = 5;

    
Value of the DAY_OF_WEEK field indicating Friday. 
/**
     * Value of the {@link #DAY_OF_WEEK} field indicating
     * Friday.
     */
    public static final int FRIDAY = 6;

    
Value of the DAY_OF_WEEK field indicating Saturday. 
/**
     * Value of the {@link #DAY_OF_WEEK} field indicating
     * Saturday.
     */
    public static final int SATURDAY = 7;

    
Value of the MONTH field indicating the first month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * first month of the year in the Gregorian and Julian calendars.
     */
    public static final int JANUARY = 0;

    
Value of the MONTH field indicating the second month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * second month of the year in the Gregorian and Julian calendars.
     */
    public static final int FEBRUARY = 1;

    
Value of the MONTH field indicating the third month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * third month of the year in the Gregorian and Julian calendars.
     */
    public static final int MARCH = 2;

    
Value of the MONTH field indicating the fourth month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * fourth month of the year in the Gregorian and Julian calendars.
     */
    public static final int APRIL = 3;

    
Value of the MONTH field indicating the fifth month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * fifth month of the year in the Gregorian and Julian calendars.
     */
    public static final int MAY = 4;

    
Value of the MONTH field indicating the sixth month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * sixth month of the year in the Gregorian and Julian calendars.
     */
    public static final int JUNE = 5;

    
Value of the MONTH field indicating the seventh month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * seventh month of the year in the Gregorian and Julian calendars.
     */
    public static final int JULY = 6;

    
Value of the MONTH field indicating the eighth month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * eighth month of the year in the Gregorian and Julian calendars.
     */
    public static final int AUGUST = 7;

    
Value of the MONTH field indicating the ninth month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * ninth month of the year in the Gregorian and Julian calendars.
     */
    public static final int SEPTEMBER = 8;

    
Value of the MONTH field indicating the tenth month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * tenth month of the year in the Gregorian and Julian calendars.
     */
    public static final int OCTOBER = 9;

    
Value of the MONTH field indicating the eleventh month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * eleventh month of the year in the Gregorian and Julian calendars.
     */
    public static final int NOVEMBER = 10;

    
Value of the MONTH field indicating the twelfth month of the year in the Gregorian and Julian calendars. 
/**
     * Value of the {@link #MONTH} field indicating the
     * twelfth month of the year in the Gregorian and Julian calendars.
     */
    public static final int DECEMBER = 11;

    
Value of the MONTH field indicating the thirteenth month of the year. Although GregorianCalendar
does not use this value, lunar calendars do.

/**
     * Value of the {@link #MONTH} field indicating the
     * thirteenth month of the year. Although <code>GregorianCalendar</code>
     * does not use this value, lunar calendars do.
     */
    public static final int UNDECIMBER = 12;

    
Value of the AM_PM field indicating the period of the day from midnight to just before noon. 
/**
     * Value of the {@link #AM_PM} field indicating the
     * period of the day from midnight to just before noon.
     */
    public static final int AM = 0;

    
Value of the AM_PM field indicating the period of the day from noon to just before midnight. 
/**
     * Value of the {@link #AM_PM} field indicating the
     * period of the day from noon to just before midnight.
     */
    public static final int PM = 1;

    
A style specifier for 
getDisplayNames indicating names in all styles, such as "January" and "Jan". 
See Also:
Since:1.6
/**
     * A style specifier for {@link #getDisplayNames(int, int, Locale)
     * getDisplayNames} indicating names in all styles, such as
     * "January" and "Jan".
     *
     * @see #SHORT_FORMAT
     * @see #LONG_FORMAT
     * @see #SHORT_STANDALONE
     * @see #LONG_STANDALONE
     * @see #SHORT
     * @see #LONG
     * @since 1.6
     */
    public static final int ALL_STYLES = 0;

    static final int STANDALONE_MASK = 0x8000;

    
A style specifier for 
getDisplayName and 
getDisplayNames equivalent to SHORT_FORMAT. 
See Also:
Since:1.6
/**
     * A style specifier for {@link #getDisplayName(int, int, Locale)
     * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
     * getDisplayNames} equivalent to {@link #SHORT_FORMAT}.
     *
     * @see #SHORT_STANDALONE
     * @see #LONG
     * @since 1.6
     */
    public static final int SHORT = 1;

    
A style specifier for 
getDisplayName and 
getDisplayNames equivalent to LONG_FORMAT. 
See Also:
Since:1.6
/**
     * A style specifier for {@link #getDisplayName(int, int, Locale)
     * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
     * getDisplayNames} equivalent to {@link #LONG_FORMAT}.
     *
     * @see #LONG_STANDALONE
     * @see #SHORT
     * @since 1.6
     */
    public static final int LONG = 2;

    
A style specifier for 
getDisplayName and 
getDisplayNames indicating a narrow name used for format. Narrow names are typically single character strings, such as "M" for Monday. 
See Also:
Since:1.8
/**
     * A style specifier for {@link #getDisplayName(int, int, Locale)
     * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
     * getDisplayNames} indicating a narrow name used for format. Narrow names
     * are typically single character strings, such as "M" for Monday.
     *
     * @see #NARROW_STANDALONE
     * @see #SHORT_FORMAT
     * @see #LONG_FORMAT
     * @since 1.8
     */
    public static final int NARROW_FORMAT = 4;

    
A style specifier for 
getDisplayName and 
getDisplayNames indicating a narrow name independently. Narrow names are typically single character strings, such as "M" for Monday. 
See Also:
Since:1.8
/**
     * A style specifier for {@link #getDisplayName(int, int, Locale)
     * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
     * getDisplayNames} indicating a narrow name independently. Narrow names
     * are typically single character strings, such as "M" for Monday.
     *
     * @see #NARROW_FORMAT
     * @see #SHORT_STANDALONE
     * @see #LONG_STANDALONE
     * @since 1.8
     */
    public static final int NARROW_STANDALONE = NARROW_FORMAT | STANDALONE_MASK;

    
A style specifier for 
getDisplayName and 
getDisplayNames indicating a short name used for format. 
See Also:
Since:1.8
/**
     * A style specifier for {@link #getDisplayName(int, int, Locale)
     * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
     * getDisplayNames} indicating a short name used for format.
     *
     * @see #SHORT_STANDALONE
     * @see #LONG_FORMAT
     * @see #LONG_STANDALONE
     * @since 1.8
     */
    public static final int SHORT_FORMAT = 1;

    
A style specifier for 
getDisplayName and 
getDisplayNames indicating a long name used for format. 
See Also:
Since:1.8
/**
     * A style specifier for {@link #getDisplayName(int, int, Locale)
     * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
     * getDisplayNames} indicating a long name used for format.
     *
     * @see #LONG_STANDALONE
     * @see #SHORT_FORMAT
     * @see #SHORT_STANDALONE
     * @since 1.8
     */
    public static final int LONG_FORMAT = 2;

    
A style specifier for 
getDisplayName and 
getDisplayNames indicating a short name used independently, such as a month abbreviation as calendar headers. 
See Also:
Since:1.8
/**
     * A style specifier for {@link #getDisplayName(int, int, Locale)
     * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
     * getDisplayNames} indicating a short name used independently,
     * such as a month abbreviation as calendar headers.
     *
     * @see #SHORT_FORMAT
     * @see #LONG_FORMAT
     * @see #LONG_STANDALONE
     * @since 1.8
     */
    public static final int SHORT_STANDALONE = SHORT | STANDALONE_MASK;

    
A style specifier for 
getDisplayName and 
getDisplayNames indicating a long name used independently, such as a month name as calendar headers. 
See Also:
Since:1.8
/**
     * A style specifier for {@link #getDisplayName(int, int, Locale)
     * getDisplayName} and {@link #getDisplayNames(int, int, Locale)
     * getDisplayNames} indicating a long name used independently,
     * such as a month name as calendar headers.
     *
     * @see #LONG_FORMAT
     * @see #SHORT_FORMAT
     * @see #SHORT_STANDALONE
     * @since 1.8
     */
    public static final int LONG_STANDALONE = LONG | STANDALONE_MASK;

    // Internal notes:
    // Calendar contains two kinds of time representations: current "time" in
    // milliseconds, and a set of calendar "fields" representing the current time.
    // The two representations are usually in sync, but can get out of sync
    // as follows.
    // 1. Initially, no fields are set, and the time is invalid.
    // 2. If the time is set, all fields are computed and in sync.
    // 3. If a single field is set, the time is invalid.
    // Recomputation of the time and fields happens when the object needs
    // to return a result to the user, or use a result for a computation.

    
The calendar field values for the currently set time for this calendar.
This is an array of FIELD_COUNT integers, with index values
ERA through DST_OFFSET.

@serial
/**
     * The calendar field values for the currently set time for this calendar.
     * This is an array of <code>FIELD_COUNT</code> integers, with index values
     * <code>ERA</code> through <code>DST_OFFSET</code>.
     * @serial
     */
    @SuppressWarnings("ProtectedField")
    protected int           fields[];

    
The flags which tell if a specified calendar field for the calendar is set.
A new object has no fields set.  After the first call to a method
which generates the fields, they all remain set after that.
This is an array of FIELD_COUNT booleans, with index values
ERA through DST_OFFSET.

@serial
/**
     * The flags which tell if a specified calendar field for the calendar is set.
     * A new object has no fields set.  After the first call to a method
     * which generates the fields, they all remain set after that.
     * This is an array of <code>FIELD_COUNT</code> booleans, with index values
     * <code>ERA</code> through <code>DST_OFFSET</code>.
     * @serial
     */
    @SuppressWarnings("ProtectedField")
    protected boolean       isSet[];

    
Pseudo-time-stamps which specify when each field was set. There
are two special values, UNSET and COMPUTED. Values from
MINIMUM_USER_SET to Integer.MAX_VALUE are legal user set values.

/**
     * Pseudo-time-stamps which specify when each field was set. There
     * are two special values, UNSET and COMPUTED. Values from
     * MINIMUM_USER_SET to Integer.MAX_VALUE are legal user set values.
     */
    private transient int   stamp[];

    
The currently set time for this calendar, expressed in milliseconds after
January 1, 1970, 0:00:00 GMT.

See Also:
  • isTimeSet
@serial
/**
     * The currently set time for this calendar, expressed in milliseconds after
     * January 1, 1970, 0:00:00 GMT.
     * @see #isTimeSet
     * @serial
     */
    @SuppressWarnings("ProtectedField")
    protected long          time;

    
True if then the value of time is valid.
The time is made invalid by a change to an item of field[].

See Also:
  • time
@serial
/**
     * True if then the value of <code>time</code> is valid.
     * The time is made invalid by a change to an item of <code>field[]</code>.
     * @see #time
     * @serial
     */
    @SuppressWarnings("ProtectedField")
    protected boolean       isTimeSet;

    
True if fields[] are in sync with the currently set time.
If false, then the next attempt to get the value of a field will
force a recomputation of all fields from the current value of
time.

@serial
/**
     * True if <code>fields[]</code> are in sync with the currently set time.
     * If false, then the next attempt to get the value of a field will
     * force a recomputation of all fields from the current value of
     * <code>time</code>.
     * @serial
     */
    @SuppressWarnings("ProtectedField")
    protected boolean       areFieldsSet;

    
True if all fields have been set.

@serial
/**
     * True if all fields have been set.
     * @serial
     */
    transient boolean       areAllFieldsSet;

    
True if this calendar allows out-of-range field values during computation
of time from fields[].

See Also:
@serial
/**
     * <code>True</code> if this calendar allows out-of-range field values during computation
     * of <code>time</code> from <code>fields[]</code>.
     * @see #setLenient
     * @see #isLenient
     * @serial
     */
    private boolean         lenient = true;

    
The TimeZone used by this calendar. Calendar
uses the time zone data to translate between locale and GMT time.

@serial
/**
     * The <code>TimeZone</code> used by this calendar. <code>Calendar</code>
     * uses the time zone data to translate between locale and GMT time.
     * @serial
     */
    private TimeZone        zone;

    
True if zone references to a shared TimeZone object.

/**
     * <code>True</code> if zone references to a shared TimeZone object.
     */
    private transient boolean sharedZone = false;

    
The first day of the week, with possible values SUNDAY,
MONDAY, etc.  This is a locale-dependent value.

@serial
/**
     * The first day of the week, with possible values <code>SUNDAY</code>,
     * <code>MONDAY</code>, etc.  This is a locale-dependent value.
     * @serial
     */
    private int             firstDayOfWeek;

    
The number of days required for the first week in a month or year,
with possible values from 1 to 7.  This is a locale-dependent value.

@serial
/**
     * The number of days required for the first week in a month or year,
     * with possible values from 1 to 7.  This is a locale-dependent value.
     * @serial
     */
    private int             minimalDaysInFirstWeek;

    
Cache to hold the firstDayOfWeek and minimalDaysInFirstWeek
of a Locale.

/**
     * Cache to hold the firstDayOfWeek and minimalDaysInFirstWeek
     * of a Locale.
     */
    private static final ConcurrentMap<Locale, int[]> cachedLocaleData
        = new ConcurrentHashMap<>(3);

    // Special values of stamp[]
    
The corresponding fields[] has no value.

/**
     * The corresponding fields[] has no value.
     */
    private static final int        UNSET = 0;

    
The value of the corresponding fields[] has been calculated internally.

/**
     * The value of the corresponding fields[] has been calculated internally.
     */
    private static final int        COMPUTED = 1;

    
The value of the corresponding fields[] has been set externally. Stamp
values which are greater than 1 represents the (pseudo) time when the
corresponding fields[] value was set.

/**
     * The value of the corresponding fields[] has been set externally. Stamp
     * values which are greater than 1 represents the (pseudo) time when the
     * corresponding fields[] value was set.
     */
    private static final int        MINIMUM_USER_STAMP = 2;

    
The mask value that represents all of the fields.

/**
     * The mask value that represents all of the fields.
     */
    static final int ALL_FIELDS = (1 << FIELD_COUNT) - 1;

    
The next available value for stamp[], an internal array.
This actually should not be written out to the stream, and will probably
be removed from the stream in the near future.  In the meantime,
a value of MINIMUM_USER_STAMP should be used.

@serial
/**
     * The next available value for <code>stamp[]</code>, an internal array.
     * This actually should not be written out to the stream, and will probably
     * be removed from the stream in the near future.  In the meantime,
     * a value of <code>MINIMUM_USER_STAMP</code> should be used.
     * @serial
     */
    private int             nextStamp = MINIMUM_USER_STAMP;

    // the internal serial version which says which version was written
    // - 0 (default) for version up to JDK 1.1.5
    // - 1 for version from JDK 1.1.6, which writes a correct 'time' value
    //     as well as compatible values for other fields.  This is a
    //     transitional format.
    // - 2 (not implemented yet) a future version, in which fields[],
    //     areFieldsSet, and isTimeSet become transient, and isSet[] is
    //     removed. In JDK 1.1.6 we write a format compatible with version 2.
    static final int        currentSerialVersion = 1;

    
The version of the serialized data on the stream.  Possible values:



0 or not present on stream



JDK 1.1.5 or earlier.



1



JDK 1.1.6 or later.  Writes a correct 'time' value
as well as compatible values for other fields.  This is a
transitional format.




When streaming out this class, the most recent format
and the highest allowable serialVersionOnStream
is written.

@serial
Since:1.1.6
/**
     * The version of the serialized data on the stream.  Possible values:
     * <dl>
     * <dt><b>0</b> or not present on stream</dt>
     * <dd>
     * JDK 1.1.5 or earlier.
     * </dd>
     * <dt><b>1</b></dt>
     * <dd>
     * JDK 1.1.6 or later.  Writes a correct 'time' value
     * as well as compatible values for other fields.  This is a
     * transitional format.
     * </dd>
     * </dl>
     * When streaming out this class, the most recent format
     * and the highest allowable <code>serialVersionOnStream</code>
     * is written.
     * @serial
     * @since 1.1.6
     */
    private int             serialVersionOnStream = currentSerialVersion;

    // Proclaim serialization compatibility with JDK 1.1
    static final long       serialVersionUID = -1807547505821590642L;

    // Mask values for calendar fields
    @SuppressWarnings("PointlessBitwiseExpression")
    static final int ERA_MASK           = (1 << ERA);
    static final int YEAR_MASK          = (1 << YEAR);
    static final int MONTH_MASK         = (1 << MONTH);
    static final int WEEK_OF_YEAR_MASK  = (1 << WEEK_OF_YEAR);
    static final int WEEK_OF_MONTH_MASK = (1 << WEEK_OF_MONTH);
    static final int DAY_OF_MONTH_MASK  = (1 << DAY_OF_MONTH);
    static final int DATE_MASK          = DAY_OF_MONTH_MASK;
    static final int DAY_OF_YEAR_MASK   = (1 << DAY_OF_YEAR);
    static final int DAY_OF_WEEK_MASK   = (1 << DAY_OF_WEEK);
    static final int DAY_OF_WEEK_IN_MONTH_MASK  = (1 << DAY_OF_WEEK_IN_MONTH);
    static final int AM_PM_MASK         = (1 << AM_PM);
    static final int HOUR_MASK          = (1 << HOUR);
    static final int HOUR_OF_DAY_MASK   = (1 << HOUR_OF_DAY);
    static final int MINUTE_MASK        = (1 << MINUTE);
    static final int SECOND_MASK        = (1 << SECOND);
    static final int MILLISECOND_MASK   = (1 << MILLISECOND);
    static final int ZONE_OFFSET_MASK   = (1 << ZONE_OFFSET);
    static final int DST_OFFSET_MASK    = (1 << DST_OFFSET);

    
Calendar.Builder is used for creating a Calendar from various date-time parameters. 
There are two ways to set a Calendar to a date-time value. One is to set the instant parameter to a millisecond offset from the Epoch. The other is to set individual field parameters, such as YEAR, to their desired values. These two ways can't be mixed. Trying to set both the instant and individual fields will cause an IllegalStateException to be thrown. However, it is permitted to override previous values of the instant or field parameters. 
If no enough field parameters are given for determining date and/or time, calendar specific default values are used when building a Calendar. For example, if the YEAR value isn't given for the Gregorian calendar, 1970 will be used. If there are any conflicts among field parameters, the  resolution rules are applied.
Therefore, the order of field setting matters.

In addition to the date-time parameters, the locale, time zone, week definition, and leniency mode parameters can be set. 
Examples

The following are sample usages. Sample code assumes that the Calendar constants are statically imported. 
The following code produces a Calendar with date 2012-12-31 (Gregorian) because Monday is the first day of a week with the  ISO 8601
compatible week parameters.

  Calendar cal = new Calendar.Builder().setCalendarType("iso8601")
                       .setWeekDate(2013, 1, MONDAY).build();


The following code produces a Japanese Calendar with date 1989-01-08 (Gregorian), assuming that the default ERA is Heisei that started on that day.

  Calendar cal = new Calendar.Builder().setCalendarType("japanese")
                       .setFields(YEAR, 1, DAY_OF_YEAR, 1).build();


See Also:
Since:1.8
/**
     * {@code Calendar.Builder} is used for creating a {@code Calendar} from
     * various date-time parameters.
     *
     * <p>There are two ways to set a {@code Calendar} to a date-time value. One
     * is to set the instant parameter to a millisecond offset from the <a
     * href="Calendar.html#Epoch">Epoch</a>. The other is to set individual
     * field parameters, such as {@link Calendar#YEAR YEAR}, to their desired
     * values. These two ways can't be mixed. Trying to set both the instant and
     * individual fields will cause an {@link IllegalStateException} to be
     * thrown. However, it is permitted to override previous values of the
     * instant or field parameters.
     *
     * <p>If no enough field parameters are given for determining date and/or
     * time, calendar specific default values are used when building a
     * {@code Calendar}. For example, if the {@link Calendar#YEAR YEAR} value
     * isn't given for the Gregorian calendar, 1970 will be used. If there are
     * any conflicts among field parameters, the <a
     * href="Calendar.html#resolution"> resolution rules</a> are applied.
     * Therefore, the order of field setting matters.
     *
     * <p>In addition to the date-time parameters,
     * the {@linkplain #setLocale(Locale) locale},
     * {@linkplain #setTimeZone(TimeZone) time zone},
     * {@linkplain #setWeekDefinition(int, int) week definition}, and
     * {@linkplain #setLenient(boolean) leniency mode} parameters can be set.
     *
     * <p><b>Examples</b>
     * <p>The following are sample usages. Sample code assumes that the
     * {@code Calendar} constants are statically imported.
     *
     * <p>The following code produces a {@code Calendar} with date 2012-12-31
     * (Gregorian) because Monday is the first day of a week with the <a
     * href="GregorianCalendar.html#iso8601_compatible_setting"> ISO 8601
     * compatible week parameters</a>.
     * <pre>
     *   Calendar cal = new Calendar.Builder().setCalendarType("iso8601")
     *                        .setWeekDate(2013, 1, MONDAY).build();</pre>
     * <p>The following code produces a Japanese {@code Calendar} with date
     * 1989-01-08 (Gregorian), assuming that the default {@link Calendar#ERA ERA}
     * is <em>Heisei</em> that started on that day.
     * <pre>
     *   Calendar cal = new Calendar.Builder().setCalendarType("japanese")
     *                        .setFields(YEAR, 1, DAY_OF_YEAR, 1).build();</pre>
     *
     * @since 1.8
     * @see Calendar#getInstance(TimeZone, Locale)
     * @see Calendar#fields
     */
    public static class Builder {
        private static final int NFIELDS = FIELD_COUNT + 1; // +1 for WEEK_YEAR
        private static final int WEEK_YEAR = FIELD_COUNT;

        private long instant;
        // Calendar.stamp[] (lower half) and Calendar.fields[] (upper half) combined
        private int[] fields;
        // Pseudo timestamp starting from MINIMUM_USER_STAMP.
        // (COMPUTED is used to indicate that the instant has been set.)
        private int nextStamp;
        // maxFieldIndex keeps the max index of fields which have been set.
        // (WEEK_YEAR is never included.)
        private int maxFieldIndex;
        private String type;
        private TimeZone zone;
        private boolean lenient = true;
        private Locale locale;
        private int firstDayOfWeek, minimalDaysInFirstWeek;

        
Constructs a Calendar.Builder. 
/**
         * Constructs a {@code Calendar.Builder}.
         */
        public Builder() {
        }

        
Sets the instant parameter to the given instant value that is a millisecond offset from the
Epoch.

Params:
  • instant – a millisecond offset from the Epoch
Throws:
See Also:
Returns:this Calendar.Builder
/**
         * Sets the instant parameter to the given {@code instant} value that is
         * a millisecond offset from <a href="Calendar.html#Epoch">the
         * Epoch</a>.
         *
         * @param instant a millisecond offset from the Epoch
         * @return this {@code Calendar.Builder}
         * @throws IllegalStateException if any of the field parameters have
         *                               already been set
         * @see Calendar#setTime(Date)
         * @see Calendar#setTimeInMillis(long)
         * @see Calendar#time
         */
        public Builder setInstant(long instant) {
            if (fields != null) {
                throw new IllegalStateException();
            }
            this.instant = instant;
            nextStamp = COMPUTED;
            return this;
        }

        
Sets the instant parameter to the instant value given by a Date. This method is equivalent to a call to setInstant(instant.getTime()). 
Params:
  • instant – a Date representing a millisecond offset from the Epoch
Throws:
See Also:
Returns:this Calendar.Builder
/**
         * Sets the instant parameter to the {@code instant} value given by a
         * {@link Date}. This method is equivalent to a call to
         * {@link #setInstant(long) setInstant(instant.getTime())}.
         *
         * @param instant a {@code Date} representing a millisecond offset from
         *                the Epoch
         * @return this {@code Calendar.Builder}
         * @throws NullPointerException  if {@code instant} is {@code null}
         * @throws IllegalStateException if any of the field parameters have
         *                               already been set
         * @see Calendar#setTime(Date)
         * @see Calendar#setTimeInMillis(long)
         * @see Calendar#time
         */
        public Builder setInstant(Date instant) {
            return setInstant(instant.getTime()); // NPE if instant == null
        }

        
Sets the field parameter to the given value. field is an index to the Calendar.fields, such as DAY_OF_MONTH. Field value validation is not performed in this method. Any out of range values are either normalized in lenient mode or detected as an invalid value in non-lenient mode when building a Calendar. 
Params:
  • field – an index to the Calendar fields
  • value – the field value
Throws:
See Also:
Returns:this Calendar.Builder
/**
         * Sets the {@code field} parameter to the given {@code value}.
         * {@code field} is an index to the {@link Calendar#fields}, such as
         * {@link Calendar#DAY_OF_MONTH DAY_OF_MONTH}. Field value validation is
         * not performed in this method. Any out of range values are either
         * normalized in lenient mode or detected as an invalid value in
         * non-lenient mode when building a {@code Calendar}.
         *
         * @param field an index to the {@code Calendar} fields
         * @param value the field value
         * @return this {@code Calendar.Builder}
         * @throws IllegalArgumentException if {@code field} is invalid
         * @throws IllegalStateException if the instant value has already been set,
         *                      or if fields have been set too many
         *                      (approximately {@link Integer#MAX_VALUE}) times.
         * @see Calendar#set(int, int)
         */
        public Builder set(int field, int value) {
            // Note: WEEK_YEAR can't be set with this method.
            if (field < 0 || field >= FIELD_COUNT) {
                throw new IllegalArgumentException("field is invalid");
            }
            if (isInstantSet()) {
                throw new IllegalStateException("instant has been set");
            }
            allocateFields();
            internalSet(field, value);
            return this;
        }

        
Sets field parameters to their values given by fieldValuePairs that are pairs of a field and its value. For example, 
  setFields(Calendar.YEAR, 2013,
            Calendar.MONTH, Calendar.DECEMBER,
            Calendar.DAY_OF_MONTH, 23);
 is equivalent to the sequence of the following set calls: 
  set(Calendar.YEAR, 2013)
  .set(Calendar.MONTH, Calendar.DECEMBER)
  .set(Calendar.DAY_OF_MONTH, 23);


Params:
  • fieldValuePairs – field-value pairs
Throws:
Returns:this Calendar.Builder
/**
         * Sets field parameters to their values given by
         * {@code fieldValuePairs} that are pairs of a field and its value.
         * For example,
         * <pre>
         *   setFields(Calendar.YEAR, 2013,
         *             Calendar.MONTH, Calendar.DECEMBER,
         *             Calendar.DAY_OF_MONTH, 23);</pre>
         * is equivalent to the sequence of the following
         * {@link #set(int, int) set} calls:
         * <pre>
         *   set(Calendar.YEAR, 2013)
         *   .set(Calendar.MONTH, Calendar.DECEMBER)
         *   .set(Calendar.DAY_OF_MONTH, 23);</pre>
         *
         * @param fieldValuePairs field-value pairs
         * @return this {@code Calendar.Builder}
         * @throws NullPointerException if {@code fieldValuePairs} is {@code null}
         * @throws IllegalArgumentException if any of fields are invalid,
         *             or if {@code fieldValuePairs.length} is an odd number.
         * @throws IllegalStateException    if the instant value has been set,
         *             or if fields have been set too many (approximately
         *             {@link Integer#MAX_VALUE}) times.
         */
        public Builder setFields(int... fieldValuePairs) {
            int len = fieldValuePairs.length;
            if ((len % 2) != 0) {
                throw new IllegalArgumentException();
            }
            if (isInstantSet()) {
                throw new IllegalStateException("instant has been set");
            }
            if ((nextStamp + len / 2) < 0) {
                throw new IllegalStateException("stamp counter overflow");
            }
            allocateFields();
            for (int i = 0; i < len; ) {
                int field = fieldValuePairs[i++];
                // Note: WEEK_YEAR can't be set with this method.
                if (field < 0 || field >= FIELD_COUNT) {
                    throw new IllegalArgumentException("field is invalid");
                }
                internalSet(field, fieldValuePairs[i++]);
            }
            return this;
        }

        
Sets the date field parameters to the values given by year, month, and dayOfMonth. This method is equivalent to a call to: 
  setFields(Calendar.YEAR, year,
            Calendar.MONTH, month,
            Calendar.DAY_OF_MONTH, dayOfMonth);


Params:
  • year –  the YEAR value
  • month –  the MONTH value (the month numbering is 0-based).
  • dayOfMonth – the DAY_OF_MONTH value
Returns:this Calendar.Builder
/**
         * Sets the date field parameters to the values given by {@code year},
         * {@code month}, and {@code dayOfMonth}. This method is equivalent to
         * a call to:
         * <pre>
         *   setFields(Calendar.YEAR, year,
         *             Calendar.MONTH, month,
         *             Calendar.DAY_OF_MONTH, dayOfMonth);</pre>
         *
         * @param year       the {@link Calendar#YEAR YEAR} value
         * @param month      the {@link Calendar#MONTH MONTH} value
         *                   (the month numbering is <em>0-based</em>).
         * @param dayOfMonth the {@link Calendar#DAY_OF_MONTH DAY_OF_MONTH} value
         * @return this {@code Calendar.Builder}
         */
        public Builder setDate(int year, int month, int dayOfMonth) {
            return setFields(YEAR, year, MONTH, month, DAY_OF_MONTH, dayOfMonth);
        }

        
Sets the time of day field parameters to the values given by hourOfDay, minute, and second. This method is equivalent to a call to: 
  setTimeOfDay(hourOfDay, minute, second, 0);


Params:
Returns:this Calendar.Builder
/**
         * Sets the time of day field parameters to the values given by
         * {@code hourOfDay}, {@code minute}, and {@code second}. This method is
         * equivalent to a call to:
         * <pre>
         *   setTimeOfDay(hourOfDay, minute, second, 0);</pre>
         *
         * @param hourOfDay the {@link Calendar#HOUR_OF_DAY HOUR_OF_DAY} value
         *                  (24-hour clock)
         * @param minute    the {@link Calendar#MINUTE MINUTE} value
         * @param second    the {@link Calendar#SECOND SECOND} value
         * @return this {@code Calendar.Builder}
         */
        public Builder setTimeOfDay(int hourOfDay, int minute, int second) {
            return setTimeOfDay(hourOfDay, minute, second, 0);
        }

        
Sets the time of day field parameters to the values given by hourOfDay, minute, second, and millis. This method is equivalent to a call to: 
  setFields(Calendar.HOUR_OF_DAY, hourOfDay,
            Calendar.MINUTE, minute,
            Calendar.SECOND, second,
            Calendar.MILLISECOND, millis);


Params:
Returns:this Calendar.Builder
/**
         * Sets the time of day field parameters to the values given by
         * {@code hourOfDay}, {@code minute}, {@code second}, and
         * {@code millis}. This method is equivalent to a call to:
         * <pre>
         *   setFields(Calendar.HOUR_OF_DAY, hourOfDay,
         *             Calendar.MINUTE, minute,
         *             Calendar.SECOND, second,
         *             Calendar.MILLISECOND, millis);</pre>
         *
         * @param hourOfDay the {@link Calendar#HOUR_OF_DAY HOUR_OF_DAY} value
         *                  (24-hour clock)
         * @param minute    the {@link Calendar#MINUTE MINUTE} value
         * @param second    the {@link Calendar#SECOND SECOND} value
         * @param millis    the {@link Calendar#MILLISECOND MILLISECOND} value
         * @return this {@code Calendar.Builder}
         */
        public Builder setTimeOfDay(int hourOfDay, int minute, int second, int millis) {
            return setFields(HOUR_OF_DAY, hourOfDay, MINUTE, minute,
                             SECOND, second, MILLISECOND, millis);
        }

        
Sets the week-based date parameters to the values with the given
date specifiers - week year, week of year, and day of week.

If the specified calendar doesn't support week dates, the build method will throw an IllegalArgumentException. 
Params:
  • weekYear –   the week year
  • weekOfYear – the week number based on weekYear
  • dayOfWeek –  the day of week value: one of the constants for the DAY_OF_WEEK field: SUNDAY, ..., SATURDAY.
See Also:
Returns:this Calendar.Builder
/**
         * Sets the week-based date parameters to the values with the given
         * date specifiers - week year, week of year, and day of week.
         *
         * <p>If the specified calendar doesn't support week dates, the
         * {@link #build() build} method will throw an {@link IllegalArgumentException}.
         *
         * @param weekYear   the week year
         * @param weekOfYear the week number based on {@code weekYear}
         * @param dayOfWeek  the day of week value: one of the constants
         *     for the {@link Calendar#DAY_OF_WEEK DAY_OF_WEEK} field:
         *     {@link Calendar#SUNDAY SUNDAY}, ..., {@link Calendar#SATURDAY SATURDAY}.
         * @return this {@code Calendar.Builder}
         * @see Calendar#setWeekDate(int, int, int)
         * @see Calendar#isWeekDateSupported()
         */
        public Builder setWeekDate(int weekYear, int weekOfYear, int dayOfWeek) {
            allocateFields();
            internalSet(WEEK_YEAR, weekYear);
            internalSet(WEEK_OF_YEAR, weekOfYear);
            internalSet(DAY_OF_WEEK, dayOfWeek);
            return this;
        }

        
Sets the time zone parameter to the given zone. If no time zone parameter is given to this Calendar.Builder, the default
TimeZone will be used in the build method. 
Params:
Throws:
See Also:
Returns:this Calendar.Builder
/**
         * Sets the time zone parameter to the given {@code zone}. If no time
         * zone parameter is given to this {@code Calendar.Builder}, the
         * {@linkplain TimeZone#getDefault() default
         * <code>TimeZone</code>} will be used in the {@link #build() build}
         * method.
         *
         * @param zone the {@link TimeZone}
         * @return this {@code Calendar.Builder}
         * @throws NullPointerException if {@code zone} is {@code null}
         * @see Calendar#setTimeZone(TimeZone)
         */
        public Builder setTimeZone(TimeZone zone) {
            if (zone == null) {
                throw new NullPointerException();
            }
            this.zone = zone;
            return this;
        }

        
Sets the lenient mode parameter to the value given by lenient. If no lenient parameter is given to this Calendar.Builder, lenient mode will be used in the build method. 
Params:
  • lenient – true for lenient mode; false for non-lenient mode
See Also:
Returns:this Calendar.Builder
/**
         * Sets the lenient mode parameter to the value given by {@code lenient}.
         * If no lenient parameter is given to this {@code Calendar.Builder},
         * lenient mode will be used in the {@link #build() build} method.
         *
         * @param lenient {@code true} for lenient mode;
         *                {@code false} for non-lenient mode
         * @return this {@code Calendar.Builder}
         * @see Calendar#setLenient(boolean)
         */
        public Builder setLenient(boolean lenient) {
            this.lenient = lenient;
            return this;
        }

        
Sets the calendar type parameter to the given type. The calendar type given by this method has precedence over any explicit or implicit calendar type given by the locale. 
In addition to the available calendar types returned by the Calendar.getAvailableCalendarTypes method, "gregorian" and "iso8601" as aliases of "gregory" can be used with this method. 
Params:
  • type – the calendar type
Throws:
See Also:
Returns:this Calendar.Builder
/**
         * Sets the calendar type parameter to the given {@code type}. The
         * calendar type given by this method has precedence over any explicit
         * or implicit calendar type given by the
         * {@linkplain #setLocale(Locale) locale}.
         *
         * <p>In addition to the available calendar types returned by the
         * {@link Calendar#getAvailableCalendarTypes() Calendar.getAvailableCalendarTypes}
         * method, {@code "gregorian"} and {@code "iso8601"} as aliases of
         * {@code "gregory"} can be used with this method.
         *
         * @param type the calendar type
         * @return this {@code Calendar.Builder}
         * @throws NullPointerException if {@code type} is {@code null}
         * @throws IllegalArgumentException if {@code type} is unknown
         * @throws IllegalStateException if another calendar type has already been set
         * @see Calendar#getCalendarType()
         * @see Calendar#getAvailableCalendarTypes()
         */
        public Builder setCalendarType(String type) {
            if (type.equals("gregorian")) { // NPE if type == null
                type = "gregory";
            }
            if (!Calendar.getAvailableCalendarTypes().contains(type)
                    && !type.equals("iso8601")) {
                throw new IllegalArgumentException("unknown calendar type: " + type);
            }
            if (this.type == null) {
                this.type = type;
            } else {
                if (!this.type.equals(type)) {
                    throw new IllegalStateException("calendar type override");
                }
            }
            return this;
        }

        
Sets the locale parameter to the given locale. If no locale is given to this Calendar.Builder, the default Locale for Category.FORMAT will be used. 
If no calendar type is explicitly given by a call to the setCalendarType method, the Locale value is used to determine what type of Calendar to be built. 
If no week definition parameters are explicitly given by a call to the setWeekDefinition method, the Locale's default values are used. 
Params:
Throws:
See Also:
Returns:this Calendar.Builder
/**
         * Sets the locale parameter to the given {@code locale}. If no locale
         * is given to this {@code Calendar.Builder}, the {@linkplain
         * Locale#getDefault(Locale.Category) default <code>Locale</code>}
         * for {@link Locale.Category#FORMAT} will be used.
         *
         * <p>If no calendar type is explicitly given by a call to the
         * {@link #setCalendarType(String) setCalendarType} method,
         * the {@code Locale} value is used to determine what type of
         * {@code Calendar} to be built.
         *
         * <p>If no week definition parameters are explicitly given by a call to
         * the {@link #setWeekDefinition(int,int) setWeekDefinition} method, the
         * {@code Locale}'s default values are used.
         *
         * @param locale the {@link Locale}
         * @throws NullPointerException if {@code locale} is {@code null}
         * @return this {@code Calendar.Builder}
         * @see Calendar#getInstance(Locale)
         */
        public Builder setLocale(Locale locale) {
            if (locale == null) {
                throw new NullPointerException();
            }
            this.locale = locale;
            return this;
        }

        
Sets the week definition parameters to the values given by firstDayOfWeek and minimalDaysInFirstWeek that are used to determine the first
week of a year. The parameters given by this method have precedence over the default values given by the locale. 
Params:
  • firstDayOfWeek – the first day of a week; one of Calendar.SUNDAY to Calendar.SATURDAY
  • minimalDaysInFirstWeek – the minimal number of days in the first
                              week (1..7)
Throws:
See Also:
Returns:this Calendar.Builder
/**
         * Sets the week definition parameters to the values given by
         * {@code firstDayOfWeek} and {@code minimalDaysInFirstWeek} that are
         * used to determine the <a href="Calendar.html#first_week">first
         * week</a> of a year. The parameters given by this method have
         * precedence over the default values given by the
         * {@linkplain #setLocale(Locale) locale}.
         *
         * @param firstDayOfWeek the first day of a week; one of
         *                       {@link Calendar#SUNDAY} to {@link Calendar#SATURDAY}
         * @param minimalDaysInFirstWeek the minimal number of days in the first
         *                               week (1..7)
         * @return this {@code Calendar.Builder}
         * @throws IllegalArgumentException if {@code firstDayOfWeek} or
         *                                  {@code minimalDaysInFirstWeek} is invalid
         * @see Calendar#getFirstDayOfWeek()
         * @see Calendar#getMinimalDaysInFirstWeek()
         */
        public Builder setWeekDefinition(int firstDayOfWeek, int minimalDaysInFirstWeek) {
            if (!isValidWeekParameter(firstDayOfWeek)
                    || !isValidWeekParameter(minimalDaysInFirstWeek)) {
                throw new IllegalArgumentException();
            }
            this.firstDayOfWeek = firstDayOfWeek;
            this.minimalDaysInFirstWeek = minimalDaysInFirstWeek;
            return this;
        }

        
Returns a Calendar built from the parameters set by the setter methods. The calendar type given by the 
setCalendarType method or the locale is used to determine what Calendar to be created. If no explicit calendar type is given, the locale's default calendar is created. 
If the calendar type is "iso8601", the Gregorian change date of a GregorianCalendar is set to Date(Long.MIN_VALUE) to be the proleptic Gregorian calendar. Its week definition
parameters are also set to be compatible
with the ISO 8601 standard. Note that the getCalendarType method of a GregorianCalendar created with "iso8601" returns "gregory". 
The default values are used for locale and time zone if these
parameters haven't been given explicitly.


If the locale contains the time zone with "tz"
Unicode extension,
and time zone hasn't been given explicitly, time zone in the locale
is used.

Any out of range field values are either normalized in lenient
mode or detected as an invalid value in non-lenient mode.

Throws:
  • IllegalArgumentException – if the calendar type is unknown, or
            if any invalid field values are given in non-lenient mode, or
            if a week date is given for the calendar type that doesn't
            support week dates.
See Also:
Returns:a Calendar built with parameters of this 
        Calendar.Builder
/**
         * Returns a {@code Calendar} built from the parameters set by the
         * setter methods. The calendar type given by the {@link #setCalendarType(String)
         * setCalendarType} method or the {@linkplain #setLocale(Locale) locale} is
         * used to determine what {@code Calendar} to be created. If no explicit
         * calendar type is given, the locale's default calendar is created.
         *
         * <p>If the calendar type is {@code "iso8601"}, the
         * {@linkplain GregorianCalendar#setGregorianChange(Date) Gregorian change date}
         * of a {@link GregorianCalendar} is set to {@code Date(Long.MIN_VALUE)}
         * to be the <em>proleptic</em> Gregorian calendar. Its week definition
         * parameters are also set to be <a
         * href="GregorianCalendar.html#iso8601_compatible_setting">compatible
         * with the ISO 8601 standard</a>. Note that the
         * {@link GregorianCalendar#getCalendarType() getCalendarType} method of
         * a {@code GregorianCalendar} created with {@code "iso8601"} returns
         * {@code "gregory"}.
         *
         * <p>The default values are used for locale and time zone if these
         * parameters haven't been given explicitly.
         * <p>
         * If the locale contains the time zone with "tz"
         * <a href="Locale.html#def_locale_extension">Unicode extension</a>,
         * and time zone hasn't been given explicitly, time zone in the locale
         * is used.
         *
         * <p>Any out of range field values are either normalized in lenient
         * mode or detected as an invalid value in non-lenient mode.
         *
         * @return a {@code Calendar} built with parameters of this {@code
         *         Calendar.Builder}
         * @throws IllegalArgumentException if the calendar type is unknown, or
         *             if any invalid field values are given in non-lenient mode, or
         *             if a week date is given for the calendar type that doesn't
         *             support week dates.
         * @see Calendar#getInstance(TimeZone, Locale)
         * @see Locale#getDefault(Locale.Category)
         * @see TimeZone#getDefault()
         */
        public Calendar build() {
            if (locale == null) {
                locale = Locale.getDefault();
            }
            if (zone == null) {
                zone = defaultTimeZone(locale);
            }
            Calendar cal;
            if (type == null) {
                type = locale.getUnicodeLocaleType("ca");
            }
            if (type == null) {
                if (locale.getCountry() == "TH"
                    && locale.getLanguage() == "th") {
                    type = "buddhist";
                } else {
                    type = "gregory";
                }
            }
            switch (type) {
            case "gregory":
                cal = new GregorianCalendar(zone, locale, true);
                break;
            case "iso8601":
                GregorianCalendar gcal = new GregorianCalendar(zone, locale, true);
                // make gcal a proleptic Gregorian
                gcal.setGregorianChange(new Date(Long.MIN_VALUE));
                // and week definition to be compatible with ISO 8601
                setWeekDefinition(MONDAY, 4);
                cal = gcal;
                break;
            case "buddhist":
                cal = new BuddhistCalendar(zone, locale);
                cal.clear();
                break;
            case "japanese":
                cal = new JapaneseImperialCalendar(zone, locale, true);
                break;
            default:
                throw new IllegalArgumentException("unknown calendar type: " + type);
            }
            cal.setLenient(lenient);
            if (firstDayOfWeek != 0) {
                cal.setFirstDayOfWeek(firstDayOfWeek);
                cal.setMinimalDaysInFirstWeek(minimalDaysInFirstWeek);
            }
            if (isInstantSet()) {
                cal.setTimeInMillis(instant);
                cal.complete();
                return cal;
            }

            if (fields != null) {
                boolean weekDate = isSet(WEEK_YEAR)
                                       && fields[WEEK_YEAR] > fields[YEAR];
                if (weekDate && !cal.isWeekDateSupported()) {
                    throw new IllegalArgumentException("week date is unsupported by " + type);
                }

                // Set the fields from the min stamp to the max stamp so that
                // the fields resolution works in the Calendar.
                for (int stamp = MINIMUM_USER_STAMP; stamp < nextStamp; stamp++) {
                    for (int index = 0; index <= maxFieldIndex; index++) {
                        if (fields[index] == stamp) {
                            cal.set(index, fields[NFIELDS + index]);
                            break;
                        }
                    }
                }

                if (weekDate) {
                    int weekOfYear = isSet(WEEK_OF_YEAR) ? fields[NFIELDS + WEEK_OF_YEAR] : 1;
                    int dayOfWeek = isSet(DAY_OF_WEEK)
                                    ? fields[NFIELDS + DAY_OF_WEEK] : cal.getFirstDayOfWeek();
                    cal.setWeekDate(fields[NFIELDS + WEEK_YEAR], weekOfYear, dayOfWeek);
                }
                cal.complete();
            }

            return cal;
        }

        private void allocateFields() {
            if (fields == null) {
                fields = new int[NFIELDS * 2];
                nextStamp = MINIMUM_USER_STAMP;
                maxFieldIndex = -1;
            }
        }

        private void internalSet(int field, int value) {
            fields[field] = nextStamp++;
            if (nextStamp < 0) {
                throw new IllegalStateException("stamp counter overflow");
            }
            fields[NFIELDS + field] = value;
            if (field > maxFieldIndex && field < WEEK_YEAR) {
                maxFieldIndex = field;
            }
        }

        private boolean isInstantSet() {
            return nextStamp == COMPUTED;
        }

        private boolean isSet(int index) {
            return fields != null && fields[index] > UNSET;
        }

        private boolean isValidWeekParameter(int value) {
            return value > 0 && value <= 7;
        }
    }

    
Constructs a Calendar with the default time zone and the default FORMAT locale. 
See Also:
/**
     * Constructs a Calendar with the default time zone
     * and the default {@link java.util.Locale.Category#FORMAT FORMAT}
     * locale.
     * @see     TimeZone#getDefault
     */
    protected Calendar()
    {
        this(TimeZone.getDefaultRef(), Locale.getDefault(Locale.Category.FORMAT));
        sharedZone = true;
    }

    
Constructs a calendar with the specified time zone and locale.

Params:
  • zone – the time zone to use
  • aLocale – the locale for the week data
/**
     * Constructs a calendar with the specified time zone and locale.
     *
     * @param zone the time zone to use
     * @param aLocale the locale for the week data
     */
    protected Calendar(TimeZone zone, Locale aLocale)
    {
        fields = new int[FIELD_COUNT];
        isSet = new boolean[FIELD_COUNT];
        stamp = new int[FIELD_COUNT];

        this.zone = zone;
        setWeekCountData(aLocale);
    }

    
Gets a calendar using the default time zone and locale. The
Calendar returned is based on the current time in the default time zone with the default FORMAT locale. 

If the locale contains the time zone with "tz"
Unicode extension,
that time zone is used instead.

Returns:a Calendar.
/**
     * Gets a calendar using the default time zone and locale. The
     * <code>Calendar</code> returned is based on the current time
     * in the default time zone with the default
     * {@link Locale.Category#FORMAT FORMAT} locale.
     * <p>
     * If the locale contains the time zone with "tz"
     * <a href="Locale.html#def_locale_extension">Unicode extension</a>,
     * that time zone is used instead.
     *
     * @return a Calendar.
     */
    public static Calendar getInstance()
    {
        Locale aLocale = Locale.getDefault(Locale.Category.FORMAT);
        return createCalendar(defaultTimeZone(aLocale), aLocale);
    }

    
Gets a calendar using the specified time zone and default locale.
The Calendar returned is based on the current time in the given time zone with the default FORMAT locale. 
Params:
  • zone – the time zone to use
Returns:a Calendar.
/**
     * Gets a calendar using the specified time zone and default locale.
     * The <code>Calendar</code> returned is based on the current time
     * in the given time zone with the default
     * {@link Locale.Category#FORMAT FORMAT} locale.
     *
     * @param zone the time zone to use
     * @return a Calendar.
     */
    public static Calendar getInstance(TimeZone zone)
    {
        return createCalendar(zone, Locale.getDefault(Locale.Category.FORMAT));
    }

    
Gets a calendar using the default time zone and specified locale.
The Calendar returned is based on the current time
in the default time zone with the given locale.


If the locale contains the time zone with "tz"
Unicode extension,
that time zone is used instead.

Params:
  • aLocale – the locale for the week data
Returns:a Calendar.
/**
     * Gets a calendar using the default time zone and specified locale.
     * The <code>Calendar</code> returned is based on the current time
     * in the default time zone with the given locale.
     * <p>
     * If the locale contains the time zone with "tz"
     * <a href="Locale.html#def_locale_extension">Unicode extension</a>,
     * that time zone is used instead.
     *
     * @param aLocale the locale for the week data
     * @return a Calendar.
     */
    public static Calendar getInstance(Locale aLocale)
    {
        return createCalendar(defaultTimeZone(aLocale), aLocale);
    }

    
Gets a calendar with the specified time zone and locale.
The Calendar returned is based on the current time
in the given time zone with the given locale.

Params:
  • zone – the time zone to use
  • aLocale – the locale for the week data
Returns:a Calendar.
/**
     * Gets a calendar with the specified time zone and locale.
     * The <code>Calendar</code> returned is based on the current time
     * in the given time zone with the given locale.
     *
     * @param zone the time zone to use
     * @param aLocale the locale for the week data
     * @return a Calendar.
     */
    public static Calendar getInstance(TimeZone zone,
                                       Locale aLocale)
    {
        return createCalendar(zone, aLocale);
    }

    private static TimeZone defaultTimeZone(Locale l) {
        TimeZone defaultTZ = TimeZone.getDefault();
        String shortTZID = l.getUnicodeLocaleType("tz");
        return shortTZID != null ?
            TimeZoneNameUtility.convertLDMLShortID(shortTZID)
                .map(TimeZone::getTimeZone)
                .orElse(defaultTZ) :
            defaultTZ;
    }

    private static Calendar createCalendar(TimeZone zone,
                                           Locale aLocale)
    {
        CalendarProvider provider =
            LocaleProviderAdapter.getAdapter(CalendarProvider.class, aLocale)
                                 .getCalendarProvider();
        if (provider != null) {
            try {
                return provider.getInstance(zone, aLocale);
            } catch (IllegalArgumentException iae) {
                // fall back to the default instantiation
            }
        }

        Calendar cal = null;

        if (aLocale.hasExtensions()) {
            String caltype = aLocale.getUnicodeLocaleType("ca");
            if (caltype != null) {
                switch (caltype) {
                case "buddhist":
                cal = new BuddhistCalendar(zone, aLocale);
                    break;
                case "japanese":
                    cal = new JapaneseImperialCalendar(zone, aLocale);
                    break;
                case "gregory":
                    cal = new GregorianCalendar(zone, aLocale);
                    break;
                }
            }
        }
        if (cal == null) {
            // If no known calendar type is explicitly specified,
            // perform the traditional way to create a Calendar:
            // create a BuddhistCalendar for th_TH locale,
            // a JapaneseImperialCalendar for ja_JP_JP locale, or
            // a GregorianCalendar for any other locales.
            // NOTE: The language, country and variant strings are interned.
            if (aLocale.getLanguage() == "th" && aLocale.getCountry() == "TH") {
                cal = new BuddhistCalendar(zone, aLocale);
            } else if (aLocale.getVariant() == "JP" && aLocale.getLanguage() == "ja"
                       && aLocale.getCountry() == "JP") {
                cal = new JapaneseImperialCalendar(zone, aLocale);
            } else {
                cal = new GregorianCalendar(zone, aLocale);
            }
        }
        return cal;
    }

    
Returns an array of all locales for which the getInstance
methods of this class can return localized instances.
The array returned must contain at least a Locale instance equal to Locale.US. 
Returns:An array of locales for which localized
        Calendar instances are available.
/**
     * Returns an array of all locales for which the <code>getInstance</code>
     * methods of this class can return localized instances.
     * The array returned must contain at least a <code>Locale</code>
     * instance equal to {@link java.util.Locale#US Locale.US}.
     *
     * @return An array of locales for which localized
     *         <code>Calendar</code> instances are available.
     */
    public static synchronized Locale[] getAvailableLocales()
    {
        return DateFormat.getAvailableLocales();
    }

    
Converts the current calendar field values in fields[] to the millisecond time value time. 
See Also:
/**
     * Converts the current calendar field values in {@link #fields fields[]}
     * to the millisecond time value
     * {@link #time}.
     *
     * @see #complete()
     * @see #computeFields()
     */
    protected abstract void computeTime();

    
Converts the current millisecond time value time to calendar field values in fields[]. This allows you to sync up the calendar field values with a new time that is set for the calendar. The time is not recomputed first; to recompute the time, then the fields, call the complete() method. 
See Also:
/**
     * Converts the current millisecond time value {@link #time}
     * to calendar field values in {@link #fields fields[]}.
     * This allows you to sync up the calendar field values with
     * a new time that is set for the calendar.  The time is <em>not</em>
     * recomputed first; to recompute the time, then the fields, call the
     * {@link #complete()} method.
     *
     * @see #computeTime()
     */
    protected abstract void computeFields();

    
Returns a Date object representing this
Calendar's time value (millisecond offset from the Epoch").

See Also:
Returns:a Date representing the time value.
/**
     * Returns a <code>Date</code> object representing this
     * <code>Calendar</code>'s time value (millisecond offset from the <a
     * href="#Epoch">Epoch</a>").
     *
     * @return a <code>Date</code> representing the time value.
     * @see #setTime(Date)
     * @see #getTimeInMillis()
     */
    public final Date getTime() {
        return new Date(getTimeInMillis());
    }

    
Sets this Calendar's time with the given Date.


Note: Calling setTime() with
Date(Long.MAX_VALUE) or Date(Long.MIN_VALUE)
may yield incorrect field values from get().

Params:
  • date – the given Date.
See Also:
/**
     * Sets this Calendar's time with the given <code>Date</code>.
     * <p>
     * Note: Calling <code>setTime()</code> with
     * <code>Date(Long.MAX_VALUE)</code> or <code>Date(Long.MIN_VALUE)</code>
     * may yield incorrect field values from <code>get()</code>.
     *
     * @param date the given Date.
     * @see #getTime()
     * @see #setTimeInMillis(long)
     */
    public final void setTime(Date date) {
        setTimeInMillis(date.getTime());
    }

    
Returns this Calendar's time value in milliseconds.

See Also:
Returns:the current time as UTC milliseconds from the epoch.
/**
     * Returns this Calendar's time value in milliseconds.
     *
     * @return the current time as UTC milliseconds from the epoch.
     * @see #getTime()
     * @see #setTimeInMillis(long)
     */
    public long getTimeInMillis() {
        if (!isTimeSet) {
            updateTime();
        }
        return time;
    }

    
Sets this Calendar's current time from the given long value.

Params:
  • millis – the new time in UTC milliseconds from the epoch.
See Also:
/**
     * Sets this Calendar's current time from the given long value.
     *
     * @param millis the new time in UTC milliseconds from the epoch.
     * @see #setTime(Date)
     * @see #getTimeInMillis()
     */
    public void setTimeInMillis(long millis) {
        // If we don't need to recalculate the calendar field values,
        // do nothing.
        if (time == millis && isTimeSet && areFieldsSet && areAllFieldsSet
            && (zone instanceof ZoneInfo) && !((ZoneInfo)zone).isDirty()) {
            return;
        }
        time = millis;
        isTimeSet = true;
        areFieldsSet = false;
        computeFields();
        areAllFieldsSet = areFieldsSet = true;
    }

    
Returns the value of the given calendar field. In lenient mode, all calendar fields are normalized. In non-lenient mode, all calendar fields are validated and this method throws an exception if any calendar fields have out-of-range values. The normalization and validation are handled by the complete() method, which process is calendar system dependent. 
Params:
  • field – the given calendar field.
Throws:
See Also:
Returns:the value for the given calendar field.
/**
     * Returns the value of the given calendar field. In lenient mode,
     * all calendar fields are normalized. In non-lenient mode, all
     * calendar fields are validated and this method throws an
     * exception if any calendar fields have out-of-range values. The
     * normalization and validation are handled by the
     * {@link #complete()} method, which process is calendar
     * system dependent.
     *
     * @param field the given calendar field.
     * @return the value for the given calendar field.
     * @throws ArrayIndexOutOfBoundsException if the specified field is out of range
     *             (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
     * @see #set(int,int)
     * @see #complete()
     */
    public int get(int field)
    {
        complete();
        return internalGet(field);
    }

    
Returns the value of the given calendar field. This method does
not involve normalization or validation of the field value.

Params:
  • field – the given calendar field.
See Also:
Returns:the value for the given calendar field.
/**
     * Returns the value of the given calendar field. This method does
     * not involve normalization or validation of the field value.
     *
     * @param field the given calendar field.
     * @return the value for the given calendar field.
     * @see #get(int)
     */
    protected final int internalGet(int field)
    {
        return fields[field];
    }

    
Sets the value of the given calendar field. This method does
not affect any setting state of the field in this
Calendar instance.

Throws:
  • IndexOutOfBoundsException – if the specified field is out of range
            (field < 0 || field >= FIELD_COUNT).
See Also:
/**
     * Sets the value of the given calendar field. This method does
     * not affect any setting state of the field in this
     * <code>Calendar</code> instance.
     *
     * @throws IndexOutOfBoundsException if the specified field is out of range
     *             (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
     * @see #areFieldsSet
     * @see #isTimeSet
     * @see #areAllFieldsSet
     * @see #set(int,int)
     */
    final void internalSet(int field, int value)
    {
        fields[field] = value;
    }

    
Sets the given calendar field to the given value. The value is not
interpreted by this method regardless of the leniency mode.

Params:
  • field – the given calendar field.
  • value – the value to be set for the given calendar field.
Throws:
See Also:
/**
     * Sets the given calendar field to the given value. The value is not
     * interpreted by this method regardless of the leniency mode.
     *
     * @param field the given calendar field.
     * @param value the value to be set for the given calendar field.
     * @throws ArrayIndexOutOfBoundsException if the specified field is out of range
     *             (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
     * in non-lenient mode.
     * @see #set(int,int,int)
     * @see #set(int,int,int,int,int)
     * @see #set(int,int,int,int,int,int)
     * @see #get(int)
     */
    public void set(int field, int value)
    {
        // If the fields are partially normalized, calculate all the
        // fields before changing any fields.
        if (areFieldsSet && !areAllFieldsSet) {
            computeFields();
        }
        internalSet(field, value);
        isTimeSet = false;
        areFieldsSet = false;
        isSet[field] = true;
        stamp[field] = nextStamp++;
        if (nextStamp == Integer.MAX_VALUE) {
            adjustStamp();
        }
    }

    
Sets the values for the calendar fields YEAR,
MONTH, and DAY_OF_MONTH. Previous values of other calendar fields are retained. If this is not desired, call clear() first. 
Params:
  • year – the value used to set the YEAR calendar field.
  • month – the value used to set the MONTH calendar field.
Month value is 0-based. e.g., 0 for January.
  • date – the value used to set the DAY_OF_MONTH calendar field.
See Also:
/**
     * Sets the values for the calendar fields <code>YEAR</code>,
     * <code>MONTH</code>, and <code>DAY_OF_MONTH</code>.
     * Previous values of other calendar fields are retained.  If this is not desired,
     * call {@link #clear()} first.
     *
     * @param year the value used to set the <code>YEAR</code> calendar field.
     * @param month the value used to set the <code>MONTH</code> calendar field.
     * Month value is 0-based. e.g., 0 for January.
     * @param date the value used to set the <code>DAY_OF_MONTH</code> calendar field.
     * @see #set(int,int)
     * @see #set(int,int,int,int,int)
     * @see #set(int,int,int,int,int,int)
     */
    public final void set(int year, int month, int date)
    {
        set(YEAR, year);
        set(MONTH, month);
        set(DATE, date);
    }

    
Sets the values for the calendar fields YEAR,
MONTH, DAY_OF_MONTH,
HOUR_OF_DAY, and MINUTE. Previous values of other fields are retained. If this is not desired, call clear() first. 
Params:
  • year – the value used to set the YEAR calendar field.
  • month – the value used to set the MONTH calendar field.
Month value is 0-based. e.g., 0 for January.
  • date – the value used to set the DAY_OF_MONTH calendar field.
  • hourOfDay – the value used to set the HOUR_OF_DAY calendar field.
  • minute – the value used to set the MINUTE calendar field.
See Also:
/**
     * Sets the values for the calendar fields <code>YEAR</code>,
     * <code>MONTH</code>, <code>DAY_OF_MONTH</code>,
     * <code>HOUR_OF_DAY</code>, and <code>MINUTE</code>.
     * Previous values of other fields are retained.  If this is not desired,
     * call {@link #clear()} first.
     *
     * @param year the value used to set the <code>YEAR</code> calendar field.
     * @param month the value used to set the <code>MONTH</code> calendar field.
     * Month value is 0-based. e.g., 0 for January.
     * @param date the value used to set the <code>DAY_OF_MONTH</code> calendar field.
     * @param hourOfDay the value used to set the <code>HOUR_OF_DAY</code> calendar field.
     * @param minute the value used to set the <code>MINUTE</code> calendar field.
     * @see #set(int,int)
     * @see #set(int,int,int)
     * @see #set(int,int,int,int,int,int)
     */
    public final void set(int year, int month, int date, int hourOfDay, int minute)
    {
        set(YEAR, year);
        set(MONTH, month);
        set(DATE, date);
        set(HOUR_OF_DAY, hourOfDay);
        set(MINUTE, minute);
    }

    
Sets the values for the fields YEAR, MONTH,
DAY_OF_MONTH, HOUR_OF_DAY, MINUTE, and
SECOND. Previous values of other fields are retained. If this is not desired, call clear() first. 
Params:
  • year – the value used to set the YEAR calendar field.
  • month – the value used to set the MONTH calendar field.
Month value is 0-based. e.g., 0 for January.
  • date – the value used to set the DAY_OF_MONTH calendar field.
  • hourOfDay – the value used to set the HOUR_OF_DAY calendar field.
  • minute – the value used to set the MINUTE calendar field.
  • second – the value used to set the SECOND calendar field.
See Also:
/**
     * Sets the values for the fields <code>YEAR</code>, <code>MONTH</code>,
     * <code>DAY_OF_MONTH</code>, <code>HOUR_OF_DAY</code>, <code>MINUTE</code>, and
     * <code>SECOND</code>.
     * Previous values of other fields are retained.  If this is not desired,
     * call {@link #clear()} first.
     *
     * @param year the value used to set the <code>YEAR</code> calendar field.
     * @param month the value used to set the <code>MONTH</code> calendar field.
     * Month value is 0-based. e.g., 0 for January.
     * @param date the value used to set the <code>DAY_OF_MONTH</code> calendar field.
     * @param hourOfDay the value used to set the <code>HOUR_OF_DAY</code> calendar field.
     * @param minute the value used to set the <code>MINUTE</code> calendar field.
     * @param second the value used to set the <code>SECOND</code> calendar field.
     * @see #set(int,int)
     * @see #set(int,int,int)
     * @see #set(int,int,int,int,int)
     */
    public final void set(int year, int month, int date, int hourOfDay, int minute,
                          int second)
    {
        set(YEAR, year);
        set(MONTH, month);
        set(DATE, date);
        set(HOUR_OF_DAY, hourOfDay);
        set(MINUTE, minute);
        set(SECOND, second);
    }

    
Sets all the calendar field values and the time value
(millisecond offset from the Epoch) of
this Calendar undefined. This means that isSet() will return false for all the
calendar fields, and the date and time calculations will treat
the fields as if they had never been set. A
Calendar implementation class may use its specific
default field values for date/time calculations. For example,
GregorianCalendar uses 1970 if the
YEAR field value is undefined.

See Also:
/**
     * Sets all the calendar field values and the time value
     * (millisecond offset from the <a href="#Epoch">Epoch</a>) of
     * this <code>Calendar</code> undefined. This means that {@link
     * #isSet(int) isSet()} will return <code>false</code> for all the
     * calendar fields, and the date and time calculations will treat
     * the fields as if they had never been set. A
     * <code>Calendar</code> implementation class may use its specific
     * default field values for date/time calculations. For example,
     * <code>GregorianCalendar</code> uses 1970 if the
     * <code>YEAR</code> field value is undefined.
     *
     * @see #clear(int)
     */
    public final void clear()
    {
        for (int i = 0; i < fields.length; ) {
            stamp[i] = fields[i] = 0; // UNSET == 0
            isSet[i++] = false;
        }
        areAllFieldsSet = areFieldsSet = false;
        isTimeSet = false;
    }

    
Sets the given calendar field value and the time value
(millisecond offset from the Epoch) of
this Calendar undefined. This means that isSet(field) will return false, and
the date and time calculations will treat the field as if it
had never been set. A Calendar implementation
class may use the field's specific default value for date and
time calculations.

The HOUR_OF_DAY, HOUR and AM_PM fields are handled independently and the the resolution rule for the time of
day is applied. Clearing one of the fields doesn't reset
the hour of day value of this Calendar. Use set(Calendar.HOUR_OF_DAY, 0) to reset the hour value. 
Params:
  • field – the calendar field to be cleared.
See Also:
/**
     * Sets the given calendar field value and the time value
     * (millisecond offset from the <a href="#Epoch">Epoch</a>) of
     * this <code>Calendar</code> undefined. This means that {@link
     * #isSet(int) isSet(field)} will return <code>false</code>, and
     * the date and time calculations will treat the field as if it
     * had never been set. A <code>Calendar</code> implementation
     * class may use the field's specific default value for date and
     * time calculations.
     *
     * <p>The {@link #HOUR_OF_DAY}, {@link #HOUR} and {@link #AM_PM}
     * fields are handled independently and the <a
     * href="#time_resolution">the resolution rule for the time of
     * day</a> is applied. Clearing one of the fields doesn't reset
     * the hour of day value of this <code>Calendar</code>. Use {@link
     * #set(int,int) set(Calendar.HOUR_OF_DAY, 0)} to reset the hour
     * value.
     *
     * @param field the calendar field to be cleared.
     * @see #clear()
     */
    public final void clear(int field)
    {
        fields[field] = 0;
        stamp[field] = UNSET;
        isSet[field] = false;

        areAllFieldsSet = areFieldsSet = false;
        isTimeSet = false;
    }

    
Determines if the given calendar field has a value set,
including cases that the value has been set by internal fields
calculations triggered by a get method call.

Params:
  • field – the calendar field to test
Returns:true if the given calendar field has a value set;
false otherwise.
/**
     * Determines if the given calendar field has a value set,
     * including cases that the value has been set by internal fields
     * calculations triggered by a <code>get</code> method call.
     *
     * @param field the calendar field to test
     * @return <code>true</code> if the given calendar field has a value set;
     * <code>false</code> otherwise.
     */
    public final boolean isSet(int field)
    {
        return stamp[field] != UNSET;
    }

    
Returns the string representation of the calendar
field value in the given style and
locale.  If no string representation is
applicable, null is returned. This method calls get(field) to get the calendar field value if the string representation is
applicable to the given calendar field.

For example, if this Calendar is a
GregorianCalendar and its date is 2005-01-01, then the string representation of the MONTH field would be "January" in the long style in an English locale or "Jan" in the short style. However, no string representation would be available for the DAY_OF_MONTH field, and this method would return null.

The default implementation supports the calendar fields for which a DateFormatSymbols has names in the given locale.

Params:
Throws:
Returns:the string representation of the given field in the given style, or null if no string representation is applicable.
Since:1.6
/**
     * Returns the string representation of the calendar
     * <code>field</code> value in the given <code>style</code> and
     * <code>locale</code>.  If no string representation is
     * applicable, <code>null</code> is returned. This method calls
     * {@link Calendar#get(int) get(field)} to get the calendar
     * <code>field</code> value if the string representation is
     * applicable to the given calendar <code>field</code>.
     *
     * <p>For example, if this <code>Calendar</code> is a
     * <code>GregorianCalendar</code> and its date is 2005-01-01, then
     * the string representation of the {@link #MONTH} field would be
     * "January" in the long style in an English locale or "Jan" in
     * the short style. However, no string representation would be
     * available for the {@link #DAY_OF_MONTH} field, and this method
     * would return <code>null</code>.
     *
     * <p>The default implementation supports the calendar fields for
     * which a {@link DateFormatSymbols} has names in the given
     * <code>locale</code>.
     *
     * @param field
     *        the calendar field for which the string representation
     *        is returned
     * @param style
     *        the style applied to the string representation; one of {@link
     *        #SHORT_FORMAT} ({@link #SHORT}), {@link #SHORT_STANDALONE},
     *        {@link #LONG_FORMAT} ({@link #LONG}), {@link #LONG_STANDALONE},
     *        {@link #NARROW_FORMAT}, or {@link #NARROW_STANDALONE}.
     * @param locale
     *        the locale for the string representation
     *        (any calendar types specified by {@code locale} are ignored)
     * @return the string representation of the given
     *        {@code field} in the given {@code style}, or
     *        {@code null} if no string representation is
     *        applicable.
     * @exception IllegalArgumentException
     *        if {@code field} or {@code style} is invalid,
     *        or if this {@code Calendar} is non-lenient and any
     *        of the calendar fields have invalid values
     * @exception NullPointerException
     *        if {@code locale} is null
     * @since 1.6
     */
    public String getDisplayName(int field, int style, Locale locale) {
        if (!checkDisplayNameParams(field, style, SHORT, NARROW_FORMAT, locale,
                            ERA_MASK|MONTH_MASK|DAY_OF_WEEK_MASK|AM_PM_MASK)) {
            return null;
        }

        String calendarType = getCalendarType();
        int fieldValue = get(field);
        // the standalone/narrow styles and short era are supported only through
        // CalendarNameProviders.
        if (isStandaloneStyle(style) || isNarrowFormatStyle(style) ||
            field == ERA && (style & SHORT) == SHORT) {
            String val = CalendarDataUtility.retrieveFieldValueName(calendarType,
                                                                    field, fieldValue,
                                                                    style, locale);
            // Perform fallback here to follow the CLDR rules
            if (val == null) {
                if (isNarrowFormatStyle(style)) {
                    val = CalendarDataUtility.retrieveFieldValueName(calendarType,
                                                                     field, fieldValue,
                                                                     toStandaloneStyle(style),
                                                                     locale);
                } else if (isStandaloneStyle(style)) {
                    val = CalendarDataUtility.retrieveFieldValueName(calendarType,
                                                                     field, fieldValue,
                                                                     getBaseStyle(style),
                                                                     locale);
                }
            }
            return val;
        }

        DateFormatSymbols symbols = DateFormatSymbols.getInstance(locale);
        String[] strings = getFieldStrings(field, style, symbols);
        if (strings != null) {
            if (fieldValue < strings.length) {
                return strings[fieldValue];
            }
        }
        return null;
    }

    
Returns a Map containing all names of the calendar field in the given style and locale and their corresponding field values. For example, if this Calendar is a GregorianCalendar, the returned map would contain "Jan" to JANUARY, "Feb" to FEBRUARY, and so on, in the short style in an English locale. 
Narrow names may not be unique due to use of single characters, such as "S" for Sunday and Saturday. In that case narrow names are not included in the returned Map. 
The values of other calendar fields may be taken into account to determine a set of display names. For example, if this Calendar is a lunisolar calendar system and the year value given by the YEAR field has a leap month, this method would return month names containing the leap month name, and month names are mapped to their values specific for the year. 
The default implementation supports display names contained in a DateFormatSymbols. For example, if field is MONTH and style is ALL_STYLES, this method returns a Map containing all strings returned by DateFormatSymbols.getShortMonths() and DateFormatSymbols.getMonths(). 
Params:
Throws:
Returns:a Map containing all display names in style and locale and their field values, or null if no display names are defined for field
Since:1.6
/**
     * Returns a {@code Map} containing all names of the calendar
     * {@code field} in the given {@code style} and
     * {@code locale} and their corresponding field values. For
     * example, if this {@code Calendar} is a {@link
     * GregorianCalendar}, the returned map would contain "Jan" to
     * {@link #JANUARY}, "Feb" to {@link #FEBRUARY}, and so on, in the
     * {@linkplain #SHORT short} style in an English locale.
     *
     * <p>Narrow names may not be unique due to use of single characters,
     * such as "S" for Sunday and Saturday. In that case narrow names are not
     * included in the returned {@code Map}.
     *
     * <p>The values of other calendar fields may be taken into
     * account to determine a set of display names. For example, if
     * this {@code Calendar} is a lunisolar calendar system and
     * the year value given by the {@link #YEAR} field has a leap
     * month, this method would return month names containing the leap
     * month name, and month names are mapped to their values specific
     * for the year.
     *
     * <p>The default implementation supports display names contained in
     * a {@link DateFormatSymbols}. For example, if {@code field}
     * is {@link #MONTH} and {@code style} is {@link
     * #ALL_STYLES}, this method returns a {@code Map} containing
     * all strings returned by {@link DateFormatSymbols#getShortMonths()}
     * and {@link DateFormatSymbols#getMonths()}.
     *
     * @param field
     *        the calendar field for which the display names are returned
     * @param style
     *        the style applied to the string representation; one of {@link
     *        #SHORT_FORMAT} ({@link #SHORT}), {@link #SHORT_STANDALONE},
     *        {@link #LONG_FORMAT} ({@link #LONG}), {@link #LONG_STANDALONE},
     *        {@link #NARROW_FORMAT}, or {@link #NARROW_STANDALONE}
     * @param locale
     *        the locale for the display names
     * @return a {@code Map} containing all display names in
     *        {@code style} and {@code locale} and their
     *        field values, or {@code null} if no display names
     *        are defined for {@code field}
     * @exception IllegalArgumentException
     *        if {@code field} or {@code style} is invalid,
     *        or if this {@code Calendar} is non-lenient and any
     *        of the calendar fields have invalid values
     * @exception NullPointerException
     *        if {@code locale} is null
     * @since 1.6
     */
    public Map<String, Integer> getDisplayNames(int field, int style, Locale locale) {
        if (!checkDisplayNameParams(field, style, ALL_STYLES, NARROW_FORMAT, locale,
                                    ERA_MASK|MONTH_MASK|DAY_OF_WEEK_MASK|AM_PM_MASK)) {
            return null;
        }

        String calendarType = getCalendarType();
        if (style == ALL_STYLES || isStandaloneStyle(style) || isNarrowFormatStyle(style) ||
            field == ERA && (style & SHORT) == SHORT) {
            Map<String, Integer> map;
            map = CalendarDataUtility.retrieveFieldValueNames(calendarType, field, style, locale);

            // Perform fallback here to follow the CLDR rules
            if (map == null) {
                if (isNarrowFormatStyle(style)) {
                    map = CalendarDataUtility.retrieveFieldValueNames(calendarType, field,
                                                                      toStandaloneStyle(style), locale);
                } else if (style != ALL_STYLES) {
                    map = CalendarDataUtility.retrieveFieldValueNames(calendarType, field,
                                                                      getBaseStyle(style), locale);
                }
            }
            return map;
        }

        // SHORT or LONG
        return getDisplayNamesImpl(field, style, locale);
    }

    private Map<String,Integer> getDisplayNamesImpl(int field, int style, Locale locale) {
        DateFormatSymbols symbols = DateFormatSymbols.getInstance(locale);
        String[] strings = getFieldStrings(field, style, symbols);
        if (strings != null) {
            Map<String,Integer> names = new HashMap<>();
            for (int i = 0; i < strings.length; i++) {
                if (strings[i].isEmpty()) {
                    continue;
                }
                names.put(strings[i], i);
            }
            return names;
        }
        return null;
    }

    boolean checkDisplayNameParams(int field, int style, int minStyle, int maxStyle,
                                   Locale locale, int fieldMask) {
        int baseStyle = getBaseStyle(style); // Ignore the standalone mask
        if (field < 0 || field >= fields.length ||
            baseStyle < minStyle || baseStyle > maxStyle || baseStyle == 3) {
            throw new IllegalArgumentException();
        }
        if (locale == null) {
            throw new NullPointerException();
        }
        return isFieldSet(fieldMask, field);
    }

    private String[] getFieldStrings(int field, int style, DateFormatSymbols symbols) {
        int baseStyle = getBaseStyle(style); // ignore the standalone mask

        // DateFormatSymbols doesn't support any narrow names.
        if (baseStyle == NARROW_FORMAT) {
            return null;
        }

        String[] strings = null;
        switch (field) {
        case ERA:
            strings = symbols.getEras();
            break;

        case MONTH:
            strings = (baseStyle == LONG) ? symbols.getMonths() : symbols.getShortMonths();
            break;

        case DAY_OF_WEEK:
            strings = (baseStyle == LONG) ? symbols.getWeekdays() : symbols.getShortWeekdays();
            break;

        case AM_PM:
            strings = symbols.getAmPmStrings();
            break;
        }
        return strings;
    }

    
Fills in any unset fields in the calendar fields. First, the computeTime() method is called if the time value (millisecond offset from the Epoch) has not been calculated from calendar field values. Then, the computeFields() method is called to calculate all calendar field values. 
/**
     * Fills in any unset fields in the calendar fields. First, the {@link
     * #computeTime()} method is called if the time value (millisecond offset
     * from the <a href="#Epoch">Epoch</a>) has not been calculated from
     * calendar field values. Then, the {@link #computeFields()} method is
     * called to calculate all calendar field values.
     */
    protected void complete()
    {
        if (!isTimeSet) {
            updateTime();
        }
        if (!areFieldsSet || !areAllFieldsSet) {
            computeFields(); // fills in unset fields
            areAllFieldsSet = areFieldsSet = true;
        }
    }

    
Returns whether the value of the specified calendar field has been set
externally by calling one of the setter methods rather than by the
internal time calculation.

Throws:
See Also:
Returns:true if the field has been set externally,
false otherwise.
/**
     * Returns whether the value of the specified calendar field has been set
     * externally by calling one of the setter methods rather than by the
     * internal time calculation.
     *
     * @return <code>true</code> if the field has been set externally,
     * <code>false</code> otherwise.
     * @exception IndexOutOfBoundsException if the specified
     *                <code>field</code> is out of range
     *               (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
     * @see #selectFields()
     * @see #setFieldsComputed(int)
     */
    final boolean isExternallySet(int field) {
        return stamp[field] >= MINIMUM_USER_STAMP;
    }

    
Returns a field mask (bit mask) indicating all calendar fields that
have the state of externally or internally set.

Returns:a bit mask indicating set state fields
/**
     * Returns a field mask (bit mask) indicating all calendar fields that
     * have the state of externally or internally set.
     *
     * @return a bit mask indicating set state fields
     */
    final int getSetStateFields() {
        int mask = 0;
        for (int i = 0; i < fields.length; i++) {
            if (stamp[i] != UNSET) {
                mask |= 1 << i;
            }
        }
        return mask;
    }

    
Sets the state of the specified calendar fields to
computed. This state means that the specified calendar fields
have valid values that have been set by internal time calculation
rather than by calling one of the setter methods.

Params:
  • fieldMask – the field to be marked as computed.
Throws:
See Also:
/**
     * Sets the state of the specified calendar fields to
     * <em>computed</em>. This state means that the specified calendar fields
     * have valid values that have been set by internal time calculation
     * rather than by calling one of the setter methods.
     *
     * @param fieldMask the field to be marked as computed.
     * @exception IndexOutOfBoundsException if the specified
     *                <code>field</code> is out of range
     *               (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
     * @see #isExternallySet(int)
     * @see #selectFields()
     */
    final void setFieldsComputed(int fieldMask) {
        if (fieldMask == ALL_FIELDS) {
            for (int i = 0; i < fields.length; i++) {
                stamp[i] = COMPUTED;
                isSet[i] = true;
            }
            areFieldsSet = areAllFieldsSet = true;
        } else {
            for (int i = 0; i < fields.length; i++) {
                if ((fieldMask & 1) == 1) {
                    stamp[i] = COMPUTED;
                    isSet[i] = true;
                } else {
                    if (areAllFieldsSet && !isSet[i]) {
                        areAllFieldsSet = false;
                    }
                }
                fieldMask >>>= 1;
            }
        }
    }

    
Sets the state of the calendar fields that are not specified
by fieldMask to unset. If fieldMask
specifies all the calendar fields, then the state of this
Calendar becomes that all the calendar fields are in sync
with the time value (millisecond offset from the Epoch).

Params:
  • fieldMask – the field mask indicating which calendar fields are in
sync with the time value.
Throws:
See Also:
/**
     * Sets the state of the calendar fields that are <em>not</em> specified
     * by <code>fieldMask</code> to <em>unset</em>. If <code>fieldMask</code>
     * specifies all the calendar fields, then the state of this
     * <code>Calendar</code> becomes that all the calendar fields are in sync
     * with the time value (millisecond offset from the Epoch).
     *
     * @param fieldMask the field mask indicating which calendar fields are in
     * sync with the time value.
     * @exception IndexOutOfBoundsException if the specified
     *                <code>field</code> is out of range
     *               (<code>field &lt; 0 || field &gt;= FIELD_COUNT</code>).
     * @see #isExternallySet(int)
     * @see #selectFields()
     */
    final void setFieldsNormalized(int fieldMask) {
        if (fieldMask != ALL_FIELDS) {
            for (int i = 0; i < fields.length; i++) {
                if ((fieldMask & 1) == 0) {
                    stamp[i] = fields[i] = 0; // UNSET == 0
                    isSet[i] = false;
                }
                fieldMask >>= 1;
            }
        }

        // Some or all of the fields are in sync with the
        // milliseconds, but the stamp values are not normalized yet.
        areFieldsSet = true;
        areAllFieldsSet = false;
    }

    
Returns whether the calendar fields are partially in sync with the time
value or fully in sync but not stamp values are not normalized yet.

/**
     * Returns whether the calendar fields are partially in sync with the time
     * value or fully in sync but not stamp values are not normalized yet.
     */
    final boolean isPartiallyNormalized() {
        return areFieldsSet && !areAllFieldsSet;
    }

    
Returns whether the calendar fields are fully in sync with the time
value.

/**
     * Returns whether the calendar fields are fully in sync with the time
     * value.
     */
    final boolean isFullyNormalized() {
        return areFieldsSet && areAllFieldsSet;
    }

    
Marks this Calendar as not sync'd.

/**
     * Marks this Calendar as not sync'd.
     */
    final void setUnnormalized() {
        areFieldsSet = areAllFieldsSet = false;
    }

    
Returns whether the specified field is on in the
fieldMask.

/**
     * Returns whether the specified <code>field</code> is on in the
     * <code>fieldMask</code>.
     */
    static boolean isFieldSet(int fieldMask, int field) {
        return (fieldMask & (1 << field)) != 0;
    }

    
Returns a field mask indicating which calendar field values
to be used to calculate the time value. The calendar fields are
returned as a bit mask, each bit of which corresponds to a field, i.e.,
the mask value of field is (1 <<
field). For example, 0x26 represents the YEAR,
MONTH, and DAY_OF_MONTH fields (i.e., 0x26 is
equal to
(1<<YEAR)|(1<<MONTH)|(1<<DAY_OF_MONTH)).

This method supports the calendar fields resolution as described in
the class description. If the bit mask for a given field is on and its
field has not been set (i.e., isSet(field) is
false), then the default value of the field has to be
used, which case means that the field has been selected because the
selected combination involves the field.

See Also:
Returns:a bit mask of selected fields
/**
     * Returns a field mask indicating which calendar field values
     * to be used to calculate the time value. The calendar fields are
     * returned as a bit mask, each bit of which corresponds to a field, i.e.,
     * the mask value of <code>field</code> is <code>(1 &lt;&lt;
     * field)</code>. For example, 0x26 represents the <code>YEAR</code>,
     * <code>MONTH</code>, and <code>DAY_OF_MONTH</code> fields (i.e., 0x26 is
     * equal to
     * <code>(1&lt;&lt;YEAR)|(1&lt;&lt;MONTH)|(1&lt;&lt;DAY_OF_MONTH))</code>.
     *
     * <p>This method supports the calendar fields resolution as described in
     * the class description. If the bit mask for a given field is on and its
     * field has not been set (i.e., <code>isSet(field)</code> is
     * <code>false</code>), then the default value of the field has to be
     * used, which case means that the field has been selected because the
     * selected combination involves the field.
     *
     * @return a bit mask of selected fields
     * @see #isExternallySet(int)
     */
    final int selectFields() {
        // This implementation has been taken from the GregorianCalendar class.

        // The YEAR field must always be used regardless of its SET
        // state because YEAR is a mandatory field to determine the date
        // and the default value (EPOCH_YEAR) may change through the
        // normalization process.
        int fieldMask = YEAR_MASK;

        if (stamp[ERA] != UNSET) {
            fieldMask |= ERA_MASK;
        }
        // Find the most recent group of fields specifying the day within
        // the year.  These may be any of the following combinations:
        //   MONTH + DAY_OF_MONTH
        //   MONTH + WEEK_OF_MONTH + DAY_OF_WEEK
        //   MONTH + DAY_OF_WEEK_IN_MONTH + DAY_OF_WEEK
        //   DAY_OF_YEAR
        //   WEEK_OF_YEAR + DAY_OF_WEEK
        // We look for the most recent of the fields in each group to determine
        // the age of the group.  For groups involving a week-related field such
        // as WEEK_OF_MONTH, DAY_OF_WEEK_IN_MONTH, or WEEK_OF_YEAR, both the
        // week-related field and the DAY_OF_WEEK must be set for the group as a
        // whole to be considered.  (See bug 4153860 - liu 7/24/98.)
        int dowStamp = stamp[DAY_OF_WEEK];
        int monthStamp = stamp[MONTH];
        int domStamp = stamp[DAY_OF_MONTH];
        int womStamp = aggregateStamp(stamp[WEEK_OF_MONTH], dowStamp);
        int dowimStamp = aggregateStamp(stamp[DAY_OF_WEEK_IN_MONTH], dowStamp);
        int doyStamp = stamp[DAY_OF_YEAR];
        int woyStamp = aggregateStamp(stamp[WEEK_OF_YEAR], dowStamp);

        int bestStamp = domStamp;
        if (womStamp > bestStamp) {
            bestStamp = womStamp;
        }
        if (dowimStamp > bestStamp) {
            bestStamp = dowimStamp;
        }
        if (doyStamp > bestStamp) {
            bestStamp = doyStamp;
        }
        if (woyStamp > bestStamp) {
            bestStamp = woyStamp;
        }

        /* No complete combination exists.  Look for WEEK_OF_MONTH,
         * DAY_OF_WEEK_IN_MONTH, or WEEK_OF_YEAR alone.  Treat DAY_OF_WEEK alone
         * as DAY_OF_WEEK_IN_MONTH.
         */
        if (bestStamp == UNSET) {
            womStamp = stamp[WEEK_OF_MONTH];
            dowimStamp = Math.max(stamp[DAY_OF_WEEK_IN_MONTH], dowStamp);
            woyStamp = stamp[WEEK_OF_YEAR];
            bestStamp = Math.max(Math.max(womStamp, dowimStamp), woyStamp);

            /* Treat MONTH alone or no fields at all as DAY_OF_MONTH.  This may
             * result in bestStamp = domStamp = UNSET if no fields are set,
             * which indicates DAY_OF_MONTH.
             */
            if (bestStamp == UNSET) {
                bestStamp = domStamp = monthStamp;
            }
        }

        if (bestStamp == domStamp ||
           (bestStamp == womStamp && stamp[WEEK_OF_MONTH] >= stamp[WEEK_OF_YEAR]) ||
           (bestStamp == dowimStamp && stamp[DAY_OF_WEEK_IN_MONTH] >= stamp[WEEK_OF_YEAR])) {
            fieldMask |= MONTH_MASK;
            if (bestStamp == domStamp) {
                fieldMask |= DAY_OF_MONTH_MASK;
            } else {
                assert (bestStamp == womStamp || bestStamp == dowimStamp);
                if (dowStamp != UNSET) {
                    fieldMask |= DAY_OF_WEEK_MASK;
                }
                if (womStamp == dowimStamp) {
                    // When they are equal, give the priority to
                    // WEEK_OF_MONTH for compatibility.
                    if (stamp[WEEK_OF_MONTH] >= stamp[DAY_OF_WEEK_IN_MONTH]) {
                        fieldMask |= WEEK_OF_MONTH_MASK;
                    } else {
                        fieldMask |= DAY_OF_WEEK_IN_MONTH_MASK;
                    }
                } else {
                    if (bestStamp == womStamp) {
                        fieldMask |= WEEK_OF_MONTH_MASK;
                    } else {
                        assert (bestStamp == dowimStamp);
                        if (stamp[DAY_OF_WEEK_IN_MONTH] != UNSET) {
                            fieldMask |= DAY_OF_WEEK_IN_MONTH_MASK;
                        }
                    }
                }
            }
        } else {
            assert (bestStamp == doyStamp || bestStamp == woyStamp ||
                    bestStamp == UNSET);
            if (bestStamp == doyStamp) {
                fieldMask |= DAY_OF_YEAR_MASK;
            } else {
                assert (bestStamp == woyStamp);
                if (dowStamp != UNSET) {
                    fieldMask |= DAY_OF_WEEK_MASK;
                }
                fieldMask |= WEEK_OF_YEAR_MASK;
            }
        }

        // Find the best set of fields specifying the time of day.  There
        // are only two possibilities here; the HOUR_OF_DAY or the
        // AM_PM and the HOUR.
        int hourOfDayStamp = stamp[HOUR_OF_DAY];
        int hourStamp = aggregateStamp(stamp[HOUR], stamp[AM_PM]);
        bestStamp = (hourStamp > hourOfDayStamp) ? hourStamp : hourOfDayStamp;

        // if bestStamp is still UNSET, then take HOUR or AM_PM. (See 4846659)
        if (bestStamp == UNSET) {
            bestStamp = Math.max(stamp[HOUR], stamp[AM_PM]);
        }

        // Hours
        if (bestStamp != UNSET) {
            if (bestStamp == hourOfDayStamp) {
                fieldMask |= HOUR_OF_DAY_MASK;
            } else {
                fieldMask |= HOUR_MASK;
                if (stamp[AM_PM] != UNSET) {
                    fieldMask |= AM_PM_MASK;
                }
            }
        }
        if (stamp[MINUTE] != UNSET) {
            fieldMask |= MINUTE_MASK;
        }
        if (stamp[SECOND] != UNSET) {
            fieldMask |= SECOND_MASK;
        }
        if (stamp[MILLISECOND] != UNSET) {
            fieldMask |= MILLISECOND_MASK;
        }
        if (stamp[ZONE_OFFSET] >= MINIMUM_USER_STAMP) {
                fieldMask |= ZONE_OFFSET_MASK;
        }
        if (stamp[DST_OFFSET] >= MINIMUM_USER_STAMP) {
            fieldMask |= DST_OFFSET_MASK;
        }

        return fieldMask;
    }

    int getBaseStyle(int style) {
        return style & ~STANDALONE_MASK;
    }

    private int toStandaloneStyle(int style) {
        return style | STANDALONE_MASK;
    }

    private boolean isStandaloneStyle(int style) {
        return (style & STANDALONE_MASK) != 0;
    }

    private boolean isNarrowStyle(int style) {
        return style == NARROW_FORMAT || style == NARROW_STANDALONE;
    }

    private boolean isNarrowFormatStyle(int style) {
        return style == NARROW_FORMAT;
    }

    
Returns the pseudo-time-stamp for two fields, given their
individual pseudo-time-stamps.  If either of the fields
is unset, then the aggregate is unset.  Otherwise, the
aggregate is the later of the two stamps.

/**
     * Returns the pseudo-time-stamp for two fields, given their
     * individual pseudo-time-stamps.  If either of the fields
     * is unset, then the aggregate is unset.  Otherwise, the
     * aggregate is the later of the two stamps.
     */
    private static int aggregateStamp(int stamp_a, int stamp_b) {
        if (stamp_a == UNSET || stamp_b == UNSET) {
            return UNSET;
        }
        return (stamp_a > stamp_b) ? stamp_a : stamp_b;
    }

    
Returns an unmodifiable Set containing all calendar types supported by Calendar in the runtime environment. The available calendar types can be used for the Unicode locale extensions. The Set returned contains at least "gregory". The calendar types don't include aliases, such as "gregorian" for "gregory". 
See Also:
Returns:an unmodifiable Set containing all available calendar types
Since:1.8
/**
     * Returns an unmodifiable {@code Set} containing all calendar types
     * supported by {@code Calendar} in the runtime environment. The available
     * calendar types can be used for the <a
     * href="Locale.html#def_locale_extension">Unicode locale extensions</a>.
     * The {@code Set} returned contains at least {@code "gregory"}. The
     * calendar types don't include aliases, such as {@code "gregorian"} for
     * {@code "gregory"}.
     *
     * @return an unmodifiable {@code Set} containing all available calendar types
     * @since 1.8
     * @see #getCalendarType()
     * @see Calendar.Builder#setCalendarType(String)
     * @see Locale#getUnicodeLocaleType(String)
     */
    public static Set<String> getAvailableCalendarTypes() {
        return AvailableCalendarTypes.SET;
    }

    private static class AvailableCalendarTypes {
        private static final Set<String> SET;
        static {
            Set<String> set = new HashSet<>(3);
            set.add("gregory");
            set.add("buddhist");
            set.add("japanese");
            SET = Collections.unmodifiableSet(set);
        }
        private AvailableCalendarTypes() {
        }
    }

    
Returns the calendar type of this Calendar. Calendar types are defined by the Unicode Locale Data Markup Language (LDML)
specification.

The default implementation of this method returns the class name of this Calendar instance. Any subclasses that implement LDML-defined calendar systems should override this method to return appropriate calendar types. 
See Also:
Returns:the LDML-defined calendar type or the class name of this Calendar instance
Since:1.8
/**
     * Returns the calendar type of this {@code Calendar}. Calendar types are
     * defined by the <em>Unicode Locale Data Markup Language (LDML)</em>
     * specification.
     *
     * <p>The default implementation of this method returns the class name of
     * this {@code Calendar} instance. Any subclasses that implement
     * LDML-defined calendar systems should override this method to return
     * appropriate calendar types.
     *
     * @return the LDML-defined calendar type or the class name of this
     *         {@code Calendar} instance
     * @since 1.8
     * @see <a href="Locale.html#def_extensions">Locale extensions</a>
     * @see Locale.Builder#setLocale(Locale)
     * @see Locale.Builder#setUnicodeLocaleKeyword(String, String)
     */
    public String getCalendarType() {
        return this.getClass().getName();
    }

    
Compares this Calendar to the specified
Object.  The result is true if and only if
the argument is a Calendar object of the same calendar
system that represents the same time value (millisecond offset from the
Epoch) under the same
Calendar parameters as this object.

The Calendar parameters are the values represented
by the isLenient, getFirstDayOfWeek,
getMinimalDaysInFirstWeek and getTimeZone
methods. If there is any difference in those parameters
between the two Calendars, this method returns
false.

Use the compareTo method to compare only the time values. 
Params:
  • obj – the object to compare with.
Returns:true if this object is equal to obj;
false otherwise.
/**
     * Compares this <code>Calendar</code> to the specified
     * <code>Object</code>.  The result is <code>true</code> if and only if
     * the argument is a <code>Calendar</code> object of the same calendar
     * system that represents the same time value (millisecond offset from the
     * <a href="#Epoch">Epoch</a>) under the same
     * <code>Calendar</code> parameters as this object.
     *
     * <p>The <code>Calendar</code> parameters are the values represented
     * by the <code>isLenient</code>, <code>getFirstDayOfWeek</code>,
     * <code>getMinimalDaysInFirstWeek</code> and <code>getTimeZone</code>
     * methods. If there is any difference in those parameters
     * between the two <code>Calendar</code>s, this method returns
     * <code>false</code>.
     *
     * <p>Use the {@link #compareTo(Calendar) compareTo} method to
     * compare only the time values.
     *
     * @param obj the object to compare with.
     * @return <code>true</code> if this object is equal to <code>obj</code>;
     * <code>false</code> otherwise.
     */
    @SuppressWarnings("EqualsWhichDoesntCheckParameterClass")
    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        try {
            Calendar that = (Calendar)obj;
            return compareTo(getMillisOf(that)) == 0 &&
                lenient == that.lenient &&
                firstDayOfWeek == that.firstDayOfWeek &&
                minimalDaysInFirstWeek == that.minimalDaysInFirstWeek &&
                zone.equals(that.zone);
        } catch (Exception e) {
            // Note: GregorianCalendar.computeTime throws
            // IllegalArgumentException if the ERA value is invalid
            // even it's in lenient mode.
        }
        return false;
    }

    
Returns a hash code for this calendar.

Returns:a hash code value for this object.
Since:1.2
/**
     * Returns a hash code for this calendar.
     *
     * @return a hash code value for this object.
     * @since 1.2
     */
    @Override
    public int hashCode() {
        // 'otheritems' represents the hash code for the previous versions.
        int otheritems = (lenient ? 1 : 0)
            | (firstDayOfWeek << 1)
            | (minimalDaysInFirstWeek << 4)
            | (zone.hashCode() << 7);
        long t = getMillisOf(this);
        return (int) t ^ (int)(t >> 32) ^ otheritems;
    }

    
Returns whether this Calendar represents a time
before the time represented by the specified
Object. This method is equivalent to:


        compareTo(when) < 0


if and only if when is a Calendar
instance. Otherwise, the method returns false.

Params:
  • when – the Object to be compared
See Also:
Returns:true if the time of this
Calendar is before the time represented by
when; false otherwise.
/**
     * Returns whether this <code>Calendar</code> represents a time
     * before the time represented by the specified
     * <code>Object</code>. This method is equivalent to:
     * <pre>{@code
     *         compareTo(when) < 0
     * }</pre>
     * if and only if <code>when</code> is a <code>Calendar</code>
     * instance. Otherwise, the method returns <code>false</code>.
     *
     * @param when the <code>Object</code> to be compared
     * @return <code>true</code> if the time of this
     * <code>Calendar</code> is before the time represented by
     * <code>when</code>; <code>false</code> otherwise.
     * @see     #compareTo(Calendar)
     */
    public boolean before(Object when) {
        return when instanceof Calendar
            && compareTo((Calendar)when) < 0;
    }

    
Returns whether this Calendar represents a time
after the time represented by the specified
Object. This method is equivalent to:


        compareTo(when) > 0


if and only if when is a Calendar
instance. Otherwise, the method returns false.

Params:
  • when – the Object to be compared
See Also:
Returns:true if the time of this Calendar is
after the time represented by when; false
otherwise.
/**
     * Returns whether this <code>Calendar</code> represents a time
     * after the time represented by the specified
     * <code>Object</code>. This method is equivalent to:
     * <pre>{@code
     *         compareTo(when) > 0
     * }</pre>
     * if and only if <code>when</code> is a <code>Calendar</code>
     * instance. Otherwise, the method returns <code>false</code>.
     *
     * @param when the <code>Object</code> to be compared
     * @return <code>true</code> if the time of this <code>Calendar</code> is
     * after the time represented by <code>when</code>; <code>false</code>
     * otherwise.
     * @see     #compareTo(Calendar)
     */
    public boolean after(Object when) {
        return when instanceof Calendar
            && compareTo((Calendar)when) > 0;
    }

    
Compares the time values (millisecond offsets from the Epoch) represented by two
Calendar objects.

Params:
  • anotherCalendar – the Calendar to be compared.
Throws:
Returns:the value 0 if the time represented by the argument
is equal to the time represented by this Calendar; a value
less than 0 if the time of this Calendar is
before the time represented by the argument; and a value greater than
0 if the time of this Calendar is after the
time represented by the argument.
Since:  1.5
/**
     * Compares the time values (millisecond offsets from the <a
     * href="#Epoch">Epoch</a>) represented by two
     * <code>Calendar</code> objects.
     *
     * @param anotherCalendar the <code>Calendar</code> to be compared.
     * @return the value <code>0</code> if the time represented by the argument
     * is equal to the time represented by this <code>Calendar</code>; a value
     * less than <code>0</code> if the time of this <code>Calendar</code> is
     * before the time represented by the argument; and a value greater than
     * <code>0</code> if the time of this <code>Calendar</code> is after the
     * time represented by the argument.
     * @exception NullPointerException if the specified <code>Calendar</code> is
     *            <code>null</code>.
     * @exception IllegalArgumentException if the time value of the
     * specified <code>Calendar</code> object can't be obtained due to
     * any invalid calendar values.
     * @since   1.5
     */
    @Override
    public int compareTo(Calendar anotherCalendar) {
        return compareTo(getMillisOf(anotherCalendar));
    }

    
Adds or subtracts the specified amount of time to the given calendar field,
based on the calendar's rules. For example, to subtract 5 days from
the current time of the calendar, you can achieve it by calling:

add(Calendar.DAY_OF_MONTH, -5).

Params:
  • field – the calendar field.
  • amount – the amount of date or time to be added to the field.
See Also:
/**
     * Adds or subtracts the specified amount of time to the given calendar field,
     * based on the calendar's rules. For example, to subtract 5 days from
     * the current time of the calendar, you can achieve it by calling:
     * <p><code>add(Calendar.DAY_OF_MONTH, -5)</code>.
     *
     * @param field the calendar field.
     * @param amount the amount of date or time to be added to the field.
     * @see #roll(int,int)
     * @see #set(int,int)
     */
    public abstract void add(int field, int amount);

    
Adds or subtracts (up/down) a single unit of time on the given time
field without changing larger fields. For example, to roll the current
date up by one day, you can achieve it by calling:

roll(Calendar.DATE, true).
When rolling on the year or Calendar.YEAR field, it will roll the year
value in the range between 1 and the value returned by calling
getMaximum(Calendar.YEAR).
When rolling on the month or Calendar.MONTH field, other fields like
date might conflict and, need to be changed. For instance,
rolling the month on the date 01/31/96 will result in 02/29/96.
When rolling on the hour-in-day or Calendar.HOUR_OF_DAY field, it will
roll the hour value in the range between 0 and 23, which is zero-based.

Params:
  • field – the time field.
  • up – indicates if the value of the specified time field is to be
rolled up or rolled down. Use true if rolling up, false otherwise.
See Also:
/**
     * Adds or subtracts (up/down) a single unit of time on the given time
     * field without changing larger fields. For example, to roll the current
     * date up by one day, you can achieve it by calling:
     * <p>roll(Calendar.DATE, true).
     * When rolling on the year or Calendar.YEAR field, it will roll the year
     * value in the range between 1 and the value returned by calling
     * <code>getMaximum(Calendar.YEAR)</code>.
     * When rolling on the month or Calendar.MONTH field, other fields like
     * date might conflict and, need to be changed. For instance,
     * rolling the month on the date 01/31/96 will result in 02/29/96.
     * When rolling on the hour-in-day or Calendar.HOUR_OF_DAY field, it will
     * roll the hour value in the range between 0 and 23, which is zero-based.
     *
     * @param field the time field.
     * @param up indicates if the value of the specified time field is to be
     * rolled up or rolled down. Use true if rolling up, false otherwise.
     * @see Calendar#add(int,int)
     * @see Calendar#set(int,int)
     */
    public abstract void roll(int field, boolean up);

    
Adds the specified (signed) amount to the specified calendar field
without changing larger fields.  A negative amount means to roll
down.

NOTE:  This default implementation on Calendar just repeatedly calls the version of roll() that rolls by one unit. This may not always do the right thing. For example, if the DAY_OF_MONTH field is 31,
rolling through February will leave it set to 28.  The GregorianCalendar
version of this function takes care of this problem.  Other subclasses
should also provide overrides of this function that do the right thing.

Params:
  • field – the calendar field.
  • amount – the signed amount to add to the calendar field.
See Also:
Since:1.2
/**
     * Adds the specified (signed) amount to the specified calendar field
     * without changing larger fields.  A negative amount means to roll
     * down.
     *
     * <p>NOTE:  This default implementation on <code>Calendar</code> just repeatedly calls the
     * version of {@link #roll(int,boolean) roll()} that rolls by one unit.  This may not
     * always do the right thing.  For example, if the <code>DAY_OF_MONTH</code> field is 31,
     * rolling through February will leave it set to 28.  The <code>GregorianCalendar</code>
     * version of this function takes care of this problem.  Other subclasses
     * should also provide overrides of this function that do the right thing.
     *
     * @param field the calendar field.
     * @param amount the signed amount to add to the calendar <code>field</code>.
     * @since 1.2
     * @see #roll(int,boolean)
     * @see #add(int,int)
     * @see #set(int,int)
     */
    public void roll(int field, int amount)
    {
        while (amount > 0) {
            roll(field, true);
            amount--;
        }
        while (amount < 0) {
            roll(field, false);
            amount++;
        }
    }

    
Sets the time zone with the given time zone value.

Params:
  • value – the given time zone.
/**
     * Sets the time zone with the given time zone value.
     *
     * @param value the given time zone.
     */
    public void setTimeZone(TimeZone value)
    {
        zone = value;
        sharedZone = false;
        /* Recompute the fields from the time using the new zone.  This also
         * works if isTimeSet is false (after a call to set()).  In that case
         * the time will be computed from the fields using the new zone, then
         * the fields will get recomputed from that.  Consider the sequence of
         * calls: cal.setTimeZone(EST); cal.set(HOUR, 1); cal.setTimeZone(PST).
         * Is cal set to 1 o'clock EST or 1 o'clock PST?  Answer: PST.  More
         * generally, a call to setTimeZone() affects calls to set() BEFORE AND
         * AFTER it up to the next call to complete().
         */
        areAllFieldsSet = areFieldsSet = false;
    }

    
Gets the time zone.

Returns:the time zone object associated with this calendar.
/**
     * Gets the time zone.
     *
     * @return the time zone object associated with this calendar.
     */
    public TimeZone getTimeZone()
    {
        // If the TimeZone object is shared by other Calendar instances, then
        // create a clone.
        if (sharedZone) {
            zone = (TimeZone) zone.clone();
            sharedZone = false;
        }
        return zone;
    }

    
Returns the time zone (without cloning).

/**
     * Returns the time zone (without cloning).
     */
    TimeZone getZone() {
        return zone;
    }

    
Sets the sharedZone flag to shared.

/**
     * Sets the sharedZone flag to <code>shared</code>.
     */
    void setZoneShared(boolean shared) {
        sharedZone = shared;
    }

    
Specifies whether or not date/time interpretation is to be lenient.  With
lenient interpretation, a date such as "February 942, 1996" will be
treated as being equivalent to the 941st day after February 1, 1996.
With strict (non-lenient) interpretation, such dates will cause an exception to be
thrown. The default is lenient.

Params:
  • lenient – true if the lenient mode is to be turned
on; false if it is to be turned off.
See Also:
/**
     * Specifies whether or not date/time interpretation is to be lenient.  With
     * lenient interpretation, a date such as "February 942, 1996" will be
     * treated as being equivalent to the 941st day after February 1, 1996.
     * With strict (non-lenient) interpretation, such dates will cause an exception to be
     * thrown. The default is lenient.
     *
     * @param lenient <code>true</code> if the lenient mode is to be turned
     * on; <code>false</code> if it is to be turned off.
     * @see #isLenient()
     * @see java.text.DateFormat#setLenient
     */
    public void setLenient(boolean lenient)
    {
        this.lenient = lenient;
    }

    
Tells whether date/time interpretation is to be lenient.

See Also:
Returns:true if the interpretation mode of this calendar is lenient;
false otherwise.
/**
     * Tells whether date/time interpretation is to be lenient.
     *
     * @return <code>true</code> if the interpretation mode of this calendar is lenient;
     * <code>false</code> otherwise.
     * @see #setLenient(boolean)
     */
    public boolean isLenient()
    {
        return lenient;
    }

    
Sets what the first day of the week is; e.g., SUNDAY in the U.S.,
MONDAY in France.

Params:
  • value – the given first day of the week.
See Also:
/**
     * Sets what the first day of the week is; e.g., <code>SUNDAY</code> in the U.S.,
     * <code>MONDAY</code> in France.
     *
     * @param value the given first day of the week.
     * @see #getFirstDayOfWeek()
     * @see #getMinimalDaysInFirstWeek()
     */
    public void setFirstDayOfWeek(int value)
    {
        if (firstDayOfWeek == value) {
            return;
        }
        firstDayOfWeek = value;
        invalidateWeekFields();
    }

    
Gets what the first day of the week is; e.g., SUNDAY in the U.S.,
MONDAY in France.

See Also:
Returns:the first day of the week.
/**
     * Gets what the first day of the week is; e.g., <code>SUNDAY</code> in the U.S.,
     * <code>MONDAY</code> in France.
     *
     * @return the first day of the week.
     * @see #setFirstDayOfWeek(int)
     * @see #getMinimalDaysInFirstWeek()
     */
    public int getFirstDayOfWeek()
    {
        return firstDayOfWeek;
    }

    
Sets what the minimal days required in the first week of the year are;
For example, if the first week is defined as one that contains the first
day of the first month of a year, call this method with value 1. If it
must be a full week, use value 7.

Params:
  • value – the given minimal days required in the first week
of the year.
See Also:
/**
     * Sets what the minimal days required in the first week of the year are;
     * For example, if the first week is defined as one that contains the first
     * day of the first month of a year, call this method with value 1. If it
     * must be a full week, use value 7.
     *
     * @param value the given minimal days required in the first week
     * of the year.
     * @see #getMinimalDaysInFirstWeek()
     */
    public void setMinimalDaysInFirstWeek(int value)
    {
        if (minimalDaysInFirstWeek == value) {
            return;
        }
        minimalDaysInFirstWeek = value;
        invalidateWeekFields();
    }

    
Gets what the minimal days required in the first week of the year are;
e.g., if the first week is defined as one that contains the first day
of the first month of a year, this method returns 1. If
the minimal days required must be a full week, this method
returns 7.

See Also:
Returns:the minimal days required in the first week of the year.
/**
     * Gets what the minimal days required in the first week of the year are;
     * e.g., if the first week is defined as one that contains the first day
     * of the first month of a year, this method returns 1. If
     * the minimal days required must be a full week, this method
     * returns 7.
     *
     * @return the minimal days required in the first week of the year.
     * @see #setMinimalDaysInFirstWeek(int)
     */
    public int getMinimalDaysInFirstWeek()
    {
        return minimalDaysInFirstWeek;
    }

    
Returns whether this Calendar supports week dates. 
The default implementation of this method returns false. 
See Also:
Returns:true if this Calendar supports week dates; false otherwise.
Since:1.7
/**
     * Returns whether this {@code Calendar} supports week dates.
     *
     * <p>The default implementation of this method returns {@code false}.
     *
     * @return {@code true} if this {@code Calendar} supports week dates;
     *         {@code false} otherwise.
     * @see #getWeekYear()
     * @see #setWeekDate(int,int,int)
     * @see #getWeeksInWeekYear()
     * @since 1.7
     */
    public boolean isWeekDateSupported() {
        return false;
    }

    
Returns the week year represented by this Calendar. The week year is in sync with the week cycle. The first day of the first week is the first day of the week year. 
The default implementation of this method throws an UnsupportedOperationException. 
Throws:
See Also:
Returns:the week year of this Calendar
Since:1.7
/**
     * Returns the week year represented by this {@code Calendar}. The
     * week year is in sync with the week cycle. The {@linkplain
     * #getFirstDayOfWeek() first day of the first week} is the first
     * day of the week year.
     *
     * <p>The default implementation of this method throws an
     * {@link UnsupportedOperationException}.
     *
     * @return the week year of this {@code Calendar}
     * @exception UnsupportedOperationException
     *            if any week year numbering isn't supported
     *            in this {@code Calendar}.
     * @see #isWeekDateSupported()
     * @see #getFirstDayOfWeek()
     * @see #getMinimalDaysInFirstWeek()
     * @since 1.7
     */
    public int getWeekYear() {
        throw new UnsupportedOperationException();
    }

    
Sets the date of this Calendar with the given date specifiers - week year, week of year, and day of week. 
Unlike the set method, all of the calendar fields and time values are calculated upon return. 
If weekOfYear is out of the valid week-of-year range in weekYear, the weekYear and 
weekOfYear values are adjusted in lenient mode, or an 
IllegalArgumentException is thrown in non-lenient mode. 
The default implementation of this method throws an UnsupportedOperationException. 
Params:
  • weekYear –   the week year
  • weekOfYear – the week number based on weekYear
  • dayOfWeek –  the day of week value: one of the constants for the DAY_OF_WEEK field: SUNDAY, ..., SATURDAY.
Throws:
  • IllegalArgumentException – 
           if any of the given date specifiers is invalid
           or any of the calendar fields are inconsistent
           with the given date specifiers in non-lenient mode
  • UnsupportedOperationException –  if any week year numbering isn't supported in this Calendar.
See Also:
Since:1.7
/**
     * Sets the date of this {@code Calendar} with the given date
     * specifiers - week year, week of year, and day of week.
     *
     * <p>Unlike the {@code set} method, all of the calendar fields
     * and {@code time} values are calculated upon return.
     *
     * <p>If {@code weekOfYear} is out of the valid week-of-year range
     * in {@code weekYear}, the {@code weekYear} and {@code
     * weekOfYear} values are adjusted in lenient mode, or an {@code
     * IllegalArgumentException} is thrown in non-lenient mode.
     *
     * <p>The default implementation of this method throws an
     * {@code UnsupportedOperationException}.
     *
     * @param weekYear   the week year
     * @param weekOfYear the week number based on {@code weekYear}
     * @param dayOfWeek  the day of week value: one of the constants
     *                   for the {@link #DAY_OF_WEEK} field: {@link
     *                   #SUNDAY}, ..., {@link #SATURDAY}.
     * @exception IllegalArgumentException
     *            if any of the given date specifiers is invalid
     *            or any of the calendar fields are inconsistent
     *            with the given date specifiers in non-lenient mode
     * @exception UnsupportedOperationException
     *            if any week year numbering isn't supported in this
     *            {@code Calendar}.
     * @see #isWeekDateSupported()
     * @see #getFirstDayOfWeek()
     * @see #getMinimalDaysInFirstWeek()
     * @since 1.7
     */
    public void setWeekDate(int weekYear, int weekOfYear, int dayOfWeek) {
        throw new UnsupportedOperationException();
    }

    
Returns the number of weeks in the week year represented by this Calendar. 
The default implementation of this method throws an UnsupportedOperationException. 
Throws:
See Also:
Returns:the number of weeks in the week year.
Since:1.7
/**
     * Returns the number of weeks in the week year represented by this
     * {@code Calendar}.
     *
     * <p>The default implementation of this method throws an
     * {@code UnsupportedOperationException}.
     *
     * @return the number of weeks in the week year.
     * @exception UnsupportedOperationException
     *            if any week year numbering isn't supported in this
     *            {@code Calendar}.
     * @see #WEEK_OF_YEAR
     * @see #isWeekDateSupported()
     * @see #getWeekYear()
     * @see #getActualMaximum(int)
     * @since 1.7
     */
    public int getWeeksInWeekYear() {
        throw new UnsupportedOperationException();
    }

    
Returns the minimum value for the given calendar field of this
Calendar instance. The minimum value is defined as the smallest value returned by the get method for any possible time value. The minimum value depends on calendar system specific parameters of the instance. 
Params:
  • field – the calendar field.
See Also:
Returns:the minimum value for the given calendar field.
/**
     * Returns the minimum value for the given calendar field of this
     * <code>Calendar</code> instance. The minimum value is defined as
     * the smallest value returned by the {@link #get(int) get} method
     * for any possible time value.  The minimum value depends on
     * calendar system specific parameters of the instance.
     *
     * @param field the calendar field.
     * @return the minimum value for the given calendar field.
     * @see #getMaximum(int)
     * @see #getGreatestMinimum(int)
     * @see #getLeastMaximum(int)
     * @see #getActualMinimum(int)
     * @see #getActualMaximum(int)
     */
    public abstract int getMinimum(int field);

    
Returns the maximum value for the given calendar field of this
Calendar instance. The maximum value is defined as the largest value returned by the get method for any possible time value. The maximum value depends on calendar system specific parameters of the instance. 
Params:
  • field – the calendar field.
See Also:
Returns:the maximum value for the given calendar field.
/**
     * Returns the maximum value for the given calendar field of this
     * <code>Calendar</code> instance. The maximum value is defined as
     * the largest value returned by the {@link #get(int) get} method
     * for any possible time value. The maximum value depends on
     * calendar system specific parameters of the instance.
     *
     * @param field the calendar field.
     * @return the maximum value for the given calendar field.
     * @see #getMinimum(int)
     * @see #getGreatestMinimum(int)
     * @see #getLeastMaximum(int)
     * @see #getActualMinimum(int)
     * @see #getActualMaximum(int)
     */
    public abstract int getMaximum(int field);

    
Returns the highest minimum value for the given calendar field
of this Calendar instance. The highest minimum value is defined as the largest value returned by getActualMinimum(int) for any possible time value. The greatest minimum value depends on calendar system specific parameters of the instance. 
Params:
  • field – the calendar field.
See Also:
Returns:the highest minimum value for the given calendar field.
/**
     * Returns the highest minimum value for the given calendar field
     * of this <code>Calendar</code> instance. The highest minimum
     * value is defined as the largest value returned by {@link
     * #getActualMinimum(int)} for any possible time value. The
     * greatest minimum value depends on calendar system specific
     * parameters of the instance.
     *
     * @param field the calendar field.
     * @return the highest minimum value for the given calendar field.
     * @see #getMinimum(int)
     * @see #getMaximum(int)
     * @see #getLeastMaximum(int)
     * @see #getActualMinimum(int)
     * @see #getActualMaximum(int)
     */
    public abstract int getGreatestMinimum(int field);

    
Returns the lowest maximum value for the given calendar field
of this Calendar instance. The lowest maximum value is defined as the smallest value returned by getActualMaximum(int) for any possible time value. The least maximum value depends on calendar system specific parameters of the instance. For example, a Calendar for the
Gregorian calendar system returns 28 for the
DAY_OF_MONTH field, because the 28th is the last
day of the shortest month of this calendar, February in a
common year.

Params:
  • field – the calendar field.
See Also:
Returns:the lowest maximum value for the given calendar field.
/**
     * Returns the lowest maximum value for the given calendar field
     * of this <code>Calendar</code> instance. The lowest maximum
     * value is defined as the smallest value returned by {@link
     * #getActualMaximum(int)} for any possible time value. The least
     * maximum value depends on calendar system specific parameters of
     * the instance. For example, a <code>Calendar</code> for the
     * Gregorian calendar system returns 28 for the
     * <code>DAY_OF_MONTH</code> field, because the 28th is the last
     * day of the shortest month of this calendar, February in a
     * common year.
     *
     * @param field the calendar field.
     * @return the lowest maximum value for the given calendar field.
     * @see #getMinimum(int)
     * @see #getMaximum(int)
     * @see #getGreatestMinimum(int)
     * @see #getActualMinimum(int)
     * @see #getActualMaximum(int)
     */
    public abstract int getLeastMaximum(int field);

    
Returns the minimum value that the specified calendar field
could have, given the time value of this Calendar.

The default implementation of this method uses an iterative
algorithm to determine the actual minimum value for the
calendar field. Subclasses should, if possible, override this
with a more efficient implementation - in many cases, they can
simply return getMinimum().

Params:
  • field – the calendar field
See Also:
Returns:the minimum of the given calendar field for the time
value of this Calendar
Since:1.2
/**
     * Returns the minimum value that the specified calendar field
     * could have, given the time value of this <code>Calendar</code>.
     *
     * <p>The default implementation of this method uses an iterative
     * algorithm to determine the actual minimum value for the
     * calendar field. Subclasses should, if possible, override this
     * with a more efficient implementation - in many cases, they can
     * simply return <code>getMinimum()</code>.
     *
     * @param field the calendar field
     * @return the minimum of the given calendar field for the time
     * value of this <code>Calendar</code>
     * @see #getMinimum(int)
     * @see #getMaximum(int)
     * @see #getGreatestMinimum(int)
     * @see #getLeastMaximum(int)
     * @see #getActualMaximum(int)
     * @since 1.2
     */
    public int getActualMinimum(int field) {
        int fieldValue = getGreatestMinimum(field);
        int endValue = getMinimum(field);

        // if we know that the minimum value is always the same, just return it
        if (fieldValue == endValue) {
            return fieldValue;
        }

        // clone the calendar so we don't mess with the real one, and set it to
        // accept anything for the field values
        Calendar work = (Calendar)this.clone();
        work.setLenient(true);

        // now try each value from getLeastMaximum() to getMaximum() one by one until
        // we get a value that normalizes to another value.  The last value that
        // normalizes to itself is the actual minimum for the current date
        int result = fieldValue;

        do {
            work.set(field, fieldValue);
            if (work.get(field) != fieldValue) {
                break;
            } else {
                result = fieldValue;
                fieldValue--;
            }
        } while (fieldValue >= endValue);

        return result;
    }

    
Returns the maximum value that the specified calendar field
could have, given the time value of this
Calendar. For example, the actual maximum value of
the MONTH field is 12 in some years, and 13 in
other years in the Hebrew calendar system.

The default implementation of this method uses an iterative
algorithm to determine the actual maximum value for the
calendar field. Subclasses should, if possible, override this
with a more efficient implementation.

Params:
  • field – the calendar field
See Also:
Returns:the maximum of the given calendar field for the time
value of this Calendar
Since:1.2
/**
     * Returns the maximum value that the specified calendar field
     * could have, given the time value of this
     * <code>Calendar</code>. For example, the actual maximum value of
     * the <code>MONTH</code> field is 12 in some years, and 13 in
     * other years in the Hebrew calendar system.
     *
     * <p>The default implementation of this method uses an iterative
     * algorithm to determine the actual maximum value for the
     * calendar field. Subclasses should, if possible, override this
     * with a more efficient implementation.
     *
     * @param field the calendar field
     * @return the maximum of the given calendar field for the time
     * value of this <code>Calendar</code>
     * @see #getMinimum(int)
     * @see #getMaximum(int)
     * @see #getGreatestMinimum(int)
     * @see #getLeastMaximum(int)
     * @see #getActualMinimum(int)
     * @since 1.2
     */
    public int getActualMaximum(int field) {
        int fieldValue = getLeastMaximum(field);
        int endValue = getMaximum(field);

        // if we know that the maximum value is always the same, just return it.
        if (fieldValue == endValue) {
            return fieldValue;
        }

        // clone the calendar so we don't mess with the real one, and set it to
        // accept anything for the field values.
        Calendar work = (Calendar)this.clone();
        work.setLenient(true);

        // if we're counting weeks, set the day of the week to Sunday.  We know the
        // last week of a month or year will contain the first day of the week.
        if (field == WEEK_OF_YEAR || field == WEEK_OF_MONTH) {
            work.set(DAY_OF_WEEK, firstDayOfWeek);
        }

        // now try each value from getLeastMaximum() to getMaximum() one by one until
        // we get a value that normalizes to another value.  The last value that
        // normalizes to itself is the actual maximum for the current date
        int result = fieldValue;

        do {
            work.set(field, fieldValue);
            if (work.get(field) != fieldValue) {
                break;
            } else {
                result = fieldValue;
                fieldValue++;
            }
        } while (fieldValue <= endValue);

        return result;
    }

    
Creates and returns a copy of this object.

Returns:a copy of this object.
/**
     * Creates and returns a copy of this object.
     *
     * @return a copy of this object.
     */
    @Override
    public Object clone()
    {
        try {
            Calendar other = (Calendar) super.clone();

            other.fields = new int[FIELD_COUNT];
            other.isSet = new boolean[FIELD_COUNT];
            other.stamp = new int[FIELD_COUNT];
            for (int i = 0; i < FIELD_COUNT; i++) {
                other.fields[i] = fields[i];
                other.stamp[i] = stamp[i];
                other.isSet[i] = isSet[i];
            }
            other.zone = (TimeZone) zone.clone();
            return other;
        }
        catch (CloneNotSupportedException e) {
            // this shouldn't happen, since we are Cloneable
            throw new InternalError(e);
        }
    }

    private static final String[] FIELD_NAME = {
        "ERA", "YEAR", "MONTH", "WEEK_OF_YEAR", "WEEK_OF_MONTH", "DAY_OF_MONTH",
        "DAY_OF_YEAR", "DAY_OF_WEEK", "DAY_OF_WEEK_IN_MONTH", "AM_PM", "HOUR",
        "HOUR_OF_DAY", "MINUTE", "SECOND", "MILLISECOND", "ZONE_OFFSET",
        "DST_OFFSET"
    };

    
Returns the name of the specified calendar field.

Params:
  • field – the calendar field
Throws:
Returns:the calendar field name
/**
     * Returns the name of the specified calendar field.
     *
     * @param field the calendar field
     * @return the calendar field name
     * @exception IndexOutOfBoundsException if <code>field</code> is negative,
     * equal to or greater than {@code FIELD_COUNT}.
     */
    static String getFieldName(int field) {
        return FIELD_NAME[field];
    }

    
Return a string representation of this calendar. This method
is intended to be used only for debugging purposes, and the
format of the returned string may vary between implementations.
The returned string may be empty but may not be null.

Returns: a string representation of this calendar.
/**
     * Return a string representation of this calendar. This method
     * is intended to be used only for debugging purposes, and the
     * format of the returned string may vary between implementations.
     * The returned string may be empty but may not be <code>null</code>.
     *
     * @return  a string representation of this calendar.
     */
    @Override
    public String toString() {
        // NOTE: BuddhistCalendar.toString() interprets the string
        // produced by this method so that the Gregorian year number
        // is substituted by its B.E. year value. It relies on
        // "...,YEAR=<year>,..." or "...,YEAR=?,...".
        StringBuilder buffer = new StringBuilder(800);
        buffer.append(getClass().getName()).append('[');
        appendValue(buffer, "time", isTimeSet, time);
        buffer.append(",areFieldsSet=").append(areFieldsSet);
        buffer.append(",areAllFieldsSet=").append(areAllFieldsSet);
        buffer.append(",lenient=").append(lenient);
        buffer.append(",zone=").append(zone);
        appendValue(buffer, ",firstDayOfWeek", true, (long) firstDayOfWeek);
        appendValue(buffer, ",minimalDaysInFirstWeek", true, (long) minimalDaysInFirstWeek);
        for (int i = 0; i < FIELD_COUNT; ++i) {
            buffer.append(',');
            appendValue(buffer, FIELD_NAME[i], isSet(i), (long) fields[i]);
        }
        buffer.append(']');
        return buffer.toString();
    }

    // =======================privates===============================

    private static void appendValue(StringBuilder sb, String item, boolean valid, long value) {
        sb.append(item).append('=');
        if (valid) {
            sb.append(value);
        } else {
            sb.append('?');
        }
    }

    
Both firstDayOfWeek and minimalDaysInFirstWeek are locale-dependent.
They are used to figure out the week count for a specific date for
a given locale. These must be set when a Calendar is constructed.

Params:
  • desiredLocale – the given locale.
/**
     * Both firstDayOfWeek and minimalDaysInFirstWeek are locale-dependent.
     * They are used to figure out the week count for a specific date for
     * a given locale. These must be set when a Calendar is constructed.
     * @param desiredLocale the given locale.
     */
    private void setWeekCountData(Locale desiredLocale)
    {
        /* try to get the Locale data from the cache */
        int[] data = cachedLocaleData.get(desiredLocale);
        if (data == null) {  /* cache miss */
            data = new int[2];
            data[0] = CalendarDataUtility.retrieveFirstDayOfWeek(desiredLocale);
            data[1] = CalendarDataUtility.retrieveMinimalDaysInFirstWeek(desiredLocale);
            cachedLocaleData.putIfAbsent(desiredLocale, data);
        }
        firstDayOfWeek = data[0];
        minimalDaysInFirstWeek = data[1];
    }

    
Recomputes the time and updates the status fields isTimeSet
and areFieldsSet.  Callers should check isTimeSet and only
call this method if isTimeSet is false.

/**
     * Recomputes the time and updates the status fields isTimeSet
     * and areFieldsSet.  Callers should check isTimeSet and only
     * call this method if isTimeSet is false.
     */
    private void updateTime() {
        computeTime();
        // The areFieldsSet and areAllFieldsSet values are no longer
        // controlled here (as of 1.5).
        isTimeSet = true;
    }

    private int compareTo(long t) {
        long thisTime = getMillisOf(this);
        return (thisTime > t) ? 1 : (thisTime == t) ? 0 : -1;
    }

    private static long getMillisOf(Calendar calendar) {
        if (calendar.isTimeSet) {
            return calendar.time;
        }
        Calendar cal = (Calendar) calendar.clone();
        cal.setLenient(true);
        return cal.getTimeInMillis();
    }

    
Adjusts the stamp[] values before nextStamp overflow. nextStamp
is set to the next stamp value upon the return.

/**
     * Adjusts the stamp[] values before nextStamp overflow. nextStamp
     * is set to the next stamp value upon the return.
     */
    private void adjustStamp() {
        int max = MINIMUM_USER_STAMP;
        int newStamp = MINIMUM_USER_STAMP;

        for (;;) {
            int min = Integer.MAX_VALUE;
            for (int v : stamp) {
                if (v >= newStamp && min > v) {
                    min = v;
                }
                if (max < v) {
                    max = v;
                }
            }
            if (max != min && min == Integer.MAX_VALUE) {
                break;
            }
            for (int i = 0; i < stamp.length; i++) {
                if (stamp[i] == min) {
                    stamp[i] = newStamp;
                }
            }
            newStamp++;
            if (min == max) {
                break;
            }
        }
        nextStamp = newStamp;
    }

    
Sets the WEEK_OF_MONTH and WEEK_OF_YEAR fields to new values with the
new parameter value if they have been calculated internally.

/**
     * Sets the WEEK_OF_MONTH and WEEK_OF_YEAR fields to new values with the
     * new parameter value if they have been calculated internally.
     */
    private void invalidateWeekFields()
    {
        if (stamp[WEEK_OF_MONTH] != COMPUTED &&
            stamp[WEEK_OF_YEAR] != COMPUTED) {
            return;
        }

        // We have to check the new values of these fields after changing
        // firstDayOfWeek and/or minimalDaysInFirstWeek. If the field values
        // have been changed, then set the new values. (4822110)
        Calendar cal = (Calendar) clone();
        cal.setLenient(true);
        cal.clear(WEEK_OF_MONTH);
        cal.clear(WEEK_OF_YEAR);

        if (stamp[WEEK_OF_MONTH] == COMPUTED) {
            int weekOfMonth = cal.get(WEEK_OF_MONTH);
            if (fields[WEEK_OF_MONTH] != weekOfMonth) {
                fields[WEEK_OF_MONTH] = weekOfMonth;
            }
        }

        if (stamp[WEEK_OF_YEAR] == COMPUTED) {
            int weekOfYear = cal.get(WEEK_OF_YEAR);
            if (fields[WEEK_OF_YEAR] != weekOfYear) {
                fields[WEEK_OF_YEAR] = weekOfYear;
            }
        }
    }

    
Save the state of this object to a stream (i.e., serialize it).
Ideally, Calendar would only write out its state data and
the current time, and not write any field data out, such as
fields[], isTimeSet, areFieldsSet,
and isSet[].  nextStamp also should not be part
of the persistent state. Unfortunately, this didn't happen before JDK 1.1
shipped. To be compatible with JDK 1.1, we will always have to write out
the field values and state flags.  However, nextStamp can be
removed from the serialization stream; this will probably happen in the
near future.

/**
     * Save the state of this object to a stream (i.e., serialize it).
     *
     * Ideally, <code>Calendar</code> would only write out its state data and
     * the current time, and not write any field data out, such as
     * <code>fields[]</code>, <code>isTimeSet</code>, <code>areFieldsSet</code>,
     * and <code>isSet[]</code>.  <code>nextStamp</code> also should not be part
     * of the persistent state. Unfortunately, this didn't happen before JDK 1.1
     * shipped. To be compatible with JDK 1.1, we will always have to write out
     * the field values and state flags.  However, <code>nextStamp</code> can be
     * removed from the serialization stream; this will probably happen in the
     * near future.
     */
    private synchronized void writeObject(ObjectOutputStream stream)
         throws IOException
    {
        // Try to compute the time correctly, for the future (stream
        // version 2) in which we don't write out fields[] or isSet[].
        if (!isTimeSet) {
            try {
                updateTime();
            }
            catch (IllegalArgumentException e) {}
        }

        // If this Calendar has a ZoneInfo, save it and set a
        // SimpleTimeZone equivalent (as a single DST schedule) for
        // backward compatibility.
        TimeZone savedZone = null;
        if (zone instanceof ZoneInfo) {
            SimpleTimeZone stz = ((ZoneInfo)zone).getLastRuleInstance();
            if (stz == null) {
                stz = new SimpleTimeZone(zone.getRawOffset(), zone.getID());
            }
            savedZone = zone;
            zone = stz;
        }

        // Write out the 1.1 FCS object.
        stream.defaultWriteObject();

        // Write out the ZoneInfo object
        // 4802409: we write out even if it is null, a temporary workaround
        // the real fix for bug 4844924 in corba-iiop
        stream.writeObject(savedZone);
        if (savedZone != null) {
            zone = savedZone;
        }
    }

    private static class CalendarAccessControlContext {
        private static final AccessControlContext INSTANCE;
        static {
            RuntimePermission perm = new RuntimePermission("accessClassInPackage.sun.util.calendar");
            PermissionCollection perms = perm.newPermissionCollection();
            perms.add(perm);
            INSTANCE = new AccessControlContext(new ProtectionDomain[] {
                                                    new ProtectionDomain(null, perms)
                                                });
        }
        private CalendarAccessControlContext() {
        }
    }

    
Reconstitutes this object from a stream (i.e., deserialize it).

/**
     * Reconstitutes this object from a stream (i.e., deserialize it).
     */
    private void readObject(ObjectInputStream stream)
         throws IOException, ClassNotFoundException
    {
        final ObjectInputStream input = stream;
        input.defaultReadObject();

        stamp = new int[FIELD_COUNT];

        // Starting with version 2 (not implemented yet), we expect that
        // fields[], isSet[], isTimeSet, and areFieldsSet may not be
        // streamed out anymore.  We expect 'time' to be correct.
        if (serialVersionOnStream >= 2)
        {
            isTimeSet = true;
            if (fields == null) {
                fields = new int[FIELD_COUNT];
            }
            if (isSet == null) {
                isSet = new boolean[FIELD_COUNT];
            }
        }
        else if (serialVersionOnStream >= 0)
        {
            for (int i=0; i<FIELD_COUNT; ++i) {
                stamp[i] = isSet[i] ? COMPUTED : UNSET;
            }
        }

        serialVersionOnStream = currentSerialVersion;

        // If there's a ZoneInfo object, use it for zone.
        ZoneInfo zi = null;
        try {
            zi = AccessController.doPrivileged(
                    new PrivilegedExceptionAction<>() {
                        @Override
                        public ZoneInfo run() throws Exception {
                            return (ZoneInfo) input.readObject();
                        }
                    },
                    CalendarAccessControlContext.INSTANCE);
        } catch (PrivilegedActionException pae) {
            Exception e = pae.getException();
            if (!(e instanceof OptionalDataException)) {
                if (e instanceof RuntimeException) {
                    throw (RuntimeException) e;
                } else if (e instanceof IOException) {
                    throw (IOException) e;
                } else if (e instanceof ClassNotFoundException) {
                    throw (ClassNotFoundException) e;
                }
                throw new RuntimeException(e);
            }
        }
        if (zi != null) {
            zone = zi;
        }

        // If the deserialized object has a SimpleTimeZone, try to
        // replace it with a ZoneInfo equivalent (as of 1.4) in order
        // to be compatible with the SimpleTimeZone-based
        // implementation as much as possible.
        if (zone instanceof SimpleTimeZone) {
            String id = zone.getID();
            TimeZone tz = TimeZone.getTimeZone(id);
            if (tz != null && tz.hasSameRules(zone) && tz.getID().equals(id)) {
                zone = tz;
            }
        }
    }

    
Converts this object to an Instant. 
 The conversion creates an Instant that represents the same point on the time-line as this Calendar. 
Returns:the instant representing the same point on the time-line
Since:1.8
/**
     * Converts this object to an {@link Instant}.
     * <p>
     * The conversion creates an {@code Instant} that represents the
     * same point on the time-line as this {@code Calendar}.
     *
     * @return the instant representing the same point on the time-line
     * @since 1.8
     */
    public final Instant toInstant() {
        return Instant.ofEpochMilli(getTimeInMillis());
    }
}