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package javax.xml.datatype;

import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

import javax.xml.namespace.QName;


Immutable representation of a time span as defined in
the W3C XML Schema 1.0 specification.

A Duration object represents a period of Gregorian time,
which consists of six fields (years, months, days, hours,
minutes, and seconds) plus a sign (+/-) field.

The first five fields have non-negative (>=0) integers or null (which represents that the field is not set), and the seconds field has a non-negative decimal or null. A negative sign indicates a negative duration. 
This class provides a number of methods that make it easy
to use for the duration datatype of XML Schema 1.0 with
the errata.

Order relationship


Duration objects only have partial order, where two values A and B
maybe either:

    
 
  1. A<B (A is shorter than B) 
  2. A>B (A is longer than B) 
  3. A==B   (A and B are of the same duration)
 
  4. A<>B (Comparison between A and B is indeterminate) 


For example, 30 days cannot be meaningfully compared to one month. The compare(Duration duration) method implements this relationship. 
See the isLongerThan(Duration) method for details about the order relationship among Duration objects. 
Operations over Duration


This class provides a set of basic arithmetic operations, such
as addition, subtraction and multiplication.
Because durations don't have total order, an operation could
fail for some combinations of operations. For example, you cannot
subtract 15 days from 1 month. See the javadoc of those methods
for detailed conditions where this could happen.

Also, division of a duration by a number is not provided because the Duration class can only deal with finite precision decimal numbers. For example, one cannot represent 1 sec divided by 3. 
However, you could substitute a division by 3 with multiplying
by numbers such as 0.3 or 0.333.

Range of allowed values


 Because some operations of Duration rely on Calendar even though Duration can hold very large or very small values, some of the methods may not work correctly on such Durations. The impacted methods document their dependency on Calendar. 
Author:Joseph Fialli, Kohsuke Kawaguchi, Jeff Suttor, Sunitha Reddy
See Also:
Since:1.5
/**
 * <p>Immutable representation of a time span as defined in
 * the W3C XML Schema 1.0 specification.
 *
 * <p>A Duration object represents a period of Gregorian time,
 * which consists of six fields (years, months, days, hours,
 * minutes, and seconds) plus a sign (+/-) field.
 *
 * <p>The first five fields have non-negative ({@literal >=}0) integers or null
 * (which represents that the field is not set),
 * and the seconds field has a non-negative decimal or null.
 * A negative sign indicates a negative duration.
 *
 * <p>This class provides a number of methods that make it easy
 * to use for the duration datatype of XML Schema 1.0 with
 * the errata.
 *
 * <h2>Order relationship</h2>
 * <p>Duration objects only have partial order, where two values A and B
 * maybe either:
 * <ol>
 *  <li>A{@literal <}B (A is shorter than B)
 *  <li>A{@literal >}B (A is longer than B)
 *  <li>A==B   (A and B are of the same duration)
 *  <li>A{@literal <>}B (Comparison between A and B is indeterminate)
 * </ol>
 *
 * <p>For example, 30 days cannot be meaningfully compared to one month.
 * The {@link #compare(Duration duration)} method implements this
 * relationship.
 *
 * <p>See the {@link #isLongerThan(Duration)} method for details about
 * the order relationship among {@code Duration} objects.
 *
 * <h2>Operations over Duration</h2>
 * <p>This class provides a set of basic arithmetic operations, such
 * as addition, subtraction and multiplication.
 * Because durations don't have total order, an operation could
 * fail for some combinations of operations. For example, you cannot
 * subtract 15 days from 1 month. See the javadoc of those methods
 * for detailed conditions where this could happen.
 *
 * <p>Also, division of a duration by a number is not provided because
 * the {@code Duration} class can only deal with finite precision
 * decimal numbers. For example, one cannot represent 1 sec divided by 3.
 *
 * <p>However, you could substitute a division by 3 with multiplying
 * by numbers such as 0.3 or 0.333.
 *
 * <h2>Range of allowed values</h2>
 * <p>
 * Because some operations of {@code Duration} rely on {@link Calendar}
 * even though {@link Duration} can hold very large or very small values,
 * some of the methods may not work correctly on such {@code Duration}s.
 * The impacted methods document their dependency on {@link Calendar}.
 *
 * @author <a href="mailto:Joseph.Fialli@Sun.COM">Joseph Fialli</a>
 * @author <a href="mailto:Kohsuke.Kawaguchi@Sun.com">Kohsuke Kawaguchi</a>
 * @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
 * @author <a href="mailto:Sunitha.Reddy@Sun.com">Sunitha Reddy</a>
 * @see XMLGregorianCalendar#add(Duration)
 * @since 1.5
 */
public abstract class Duration {

    
Debugging true or false. 
/**
     * Debugging {@code true} or {@code false}.
     */
    private static final boolean DEBUG = true;

    
Default no-arg constructor.

Note: Always use the DatatypeFactory to construct an instance of Duration. The constructor on this class cannot be guaranteed to produce an object with a consistent state and may be removed in the future. 
/**
     * Default no-arg constructor.
     *
     * <p>Note: Always use the {@link DatatypeFactory} to
     * construct an instance of {@code Duration}.
     * The constructor on this class cannot be guaranteed to
     * produce an object with a consistent state and may be
     * removed in the future.
     */
    public Duration() {
    }

    
Return the name of the XML Schema date/time type that this instance maps to. Type is computed based on fields that are set, i.e. isSet(Field field) == true. 

  Required fields for XML Schema 1.0 Date/Time Datatypes.

        (timezone is optional for all date/time datatypes)
  
    

      Datatype
      year
      month
      day
      hour
      minute
      second
    

  
  
    

      DatatypeConstants.DURATION
      X
      X
      X
      X
      X
      X
    

    

      DatatypeConstants.DURATION_DAYTIME
      
      
      X
      X
      X
      X
    

    

      DatatypeConstants.DURATION_YEARMONTH
      X
      X
      
      
      
      
    

  



Throws:
  • IllegalStateException – If the combination of set fields does not match one of the XML Schema date/time datatypes.
Returns:one of the following constants: DatatypeConstants.DURATION, DatatypeConstants.DURATION_DAYTIME or DatatypeConstants.DURATION_YEARMONTH.
/**
     * Return the name of the XML Schema date/time type that this instance
     * maps to. Type is computed based on fields that are set,
     * i.e. {@link #isSet(DatatypeConstants.Field field)} == {@code true}.
     *
     * <table class="striped">
     *   <caption>Required fields for XML Schema 1.0 Date/Time Datatypes.<br>
     *         <i>(timezone is optional for all date/time datatypes)</i></caption>
     *   <thead>
     *     <tr>
     *       <th>Datatype</th>
     *       <th>year</th>
     *       <th>month</th>
     *       <th>day</th>
     *       <th>hour</th>
     *       <th>minute</th>
     *       <th>second</th>
     *     </tr>
     *   </thead>
     *   <tbody>
     *     <tr>
     *       <td>{@link DatatypeConstants#DURATION}</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *     </tr>
     *     <tr>
     *       <td>{@link DatatypeConstants#DURATION_DAYTIME}</td>
     *       <td></td>
     *       <td></td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td>X</td>
     *     </tr>
     *     <tr>
     *       <td>{@link DatatypeConstants#DURATION_YEARMONTH}</td>
     *       <td>X</td>
     *       <td>X</td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *       <td></td>
     *     </tr>
     *   </tbody>
     * </table>
     *
     * @return one of the following constants:
     *   {@link DatatypeConstants#DURATION},
     *   {@link DatatypeConstants#DURATION_DAYTIME} or
     *   {@link DatatypeConstants#DURATION_YEARMONTH}.
     *
     * @throws IllegalStateException If the combination of set fields does not match one of the XML Schema date/time datatypes.
     */
    public QName getXMLSchemaType() {

        boolean yearSet = isSet(DatatypeConstants.YEARS);
        boolean monthSet = isSet(DatatypeConstants.MONTHS);
        boolean daySet = isSet(DatatypeConstants.DAYS);
        boolean hourSet = isSet(DatatypeConstants.HOURS);
        boolean minuteSet = isSet(DatatypeConstants.MINUTES);
        boolean secondSet = isSet(DatatypeConstants.SECONDS);

        // DURATION
        if (yearSet
            && monthSet
            && daySet
            && hourSet
            && minuteSet
            && secondSet) {
            return DatatypeConstants.DURATION;
        }

        // DURATION_DAYTIME
        if (!yearSet
            && !monthSet
            && daySet
            && hourSet
            && minuteSet
            && secondSet) {
            return DatatypeConstants.DURATION_DAYTIME;
        }

        // DURATION_YEARMONTH
        if (yearSet
            && monthSet
            && !daySet
            && !hourSet
            && !minuteSet
            && !secondSet) {
            return DatatypeConstants.DURATION_YEARMONTH;
        }

        // nothing matches
        throw new IllegalStateException(
                "javax.xml.datatype.Duration#getXMLSchemaType():"
                + " this Duration does not match one of the XML Schema date/time datatypes:"
                + " year set = " + yearSet
                + " month set = " + monthSet
                + " day set = " + daySet
                + " hour set = " + hourSet
                + " minute set = " + minuteSet
                + " second set = " + secondSet
        );
    }

    
Returns the sign of this duration in -1,0, or 1.

Returns:
     -1 if this duration is negative, 0 if the duration is zero,
     and 1 if the duration is positive.
/**
     * Returns the sign of this duration in -1,0, or 1.
     *
     * @return
     *      -1 if this duration is negative, 0 if the duration is zero,
     *      and 1 if the duration is positive.
     */
    public abstract int getSign();

    
Get the years value of this Duration as an int or 0 if not present. 
getYears() is a convenience method for getField(DatatypeConstants.YEARS). 
As the return value is an int, an incorrect value will be returned for Durations with years that go beyond the range of an int. Use getField(DatatypeConstants.YEARS) to avoid possible loss of precision. 
Returns:If the years field is present, return its value as an int, else return 0.
/**
     * Get the years value of this {@code Duration} as an {@code int} or {@code 0} if not present.
     *
     * <p>{@code getYears()} is a convenience method for
     * {@link #getField(DatatypeConstants.Field field) getField(DatatypeConstants.YEARS)}.
     *
     * <p>As the return value is an {@code int}, an incorrect value will be returned for {@code Duration}s
     * with years that go beyond the range of an {@code int}.
     * Use {@link #getField(DatatypeConstants.Field field) getField(DatatypeConstants.YEARS)} to avoid possible loss of precision.
     *
     * @return If the years field is present, return its value as an {@code int}, else return {@code 0}.
     */
    public int getYears() {
        return getField(DatatypeConstants.YEARS).intValue();
    }

    
Obtains the value of the MONTHS field as an integer value, or 0 if not present. This method works just like getYears() except that this method works on the MONTHS field. 
Returns:Months of this Duration.
/**
     * Obtains the value of the MONTHS field as an integer value,
     * or 0 if not present.
     *
     * This method works just like {@link #getYears()} except
     * that this method works on the MONTHS field.
     *
     * @return Months of this {@code Duration}.
     */
    public int getMonths() {
        return getField(DatatypeConstants.MONTHS).intValue();
    }

    
Obtains the value of the DAYS field as an integer value, or 0 if not present. This method works just like getYears() except that this method works on the DAYS field. 
Returns:Days of this Duration.
/**
     * Obtains the value of the DAYS field as an integer value,
     * or 0 if not present.
     *
     * This method works just like {@link #getYears()} except
     * that this method works on the DAYS field.
     *
     * @return Days of this {@code Duration}.
     */
    public int getDays() {
        return getField(DatatypeConstants.DAYS).intValue();
    }

    
Obtains the value of the HOURS field as an integer value, or 0 if not present. This method works just like getYears() except that this method works on the HOURS field. 
Returns:Hours of this Duration.
/**
     * Obtains the value of the HOURS field as an integer value,
     * or 0 if not present.
     *
     * This method works just like {@link #getYears()} except
     * that this method works on the HOURS field.
     *
     * @return Hours of this {@code Duration}.
     *
     */
    public int getHours() {
        return getField(DatatypeConstants.HOURS).intValue();
    }

    
Obtains the value of the MINUTES field as an integer value, or 0 if not present. This method works just like getYears() except that this method works on the MINUTES field. 
Returns:Minutes of this Duration.
/**
     * Obtains the value of the MINUTES field as an integer value,
     * or 0 if not present.
     *
     * This method works just like {@link #getYears()} except
     * that this method works on the MINUTES field.
     *
     * @return Minutes of this {@code Duration}.
     *
     */
    public int getMinutes() {
        return getField(DatatypeConstants.MINUTES).intValue();
    }

    
Obtains the value of the SECONDS field as an integer value, or 0 if not present. This method works just like getYears() except that this method works on the SECONDS field. 
Returns:seconds in the integer value. The fraction of seconds
  will be discarded (for example, if the actual value is 2.5,
  this method returns 2)
/**
     * Obtains the value of the SECONDS field as an integer value,
     * or 0 if not present.
     *
     * This method works just like {@link #getYears()} except
     * that this method works on the SECONDS field.
     *
     * @return seconds in the integer value. The fraction of seconds
     *   will be discarded (for example, if the actual value is 2.5,
     *   this method returns 2)
     */
    public int getSeconds() {
        return getField(DatatypeConstants.SECONDS).intValue();
    }

    
Returns the length of the duration in milli-seconds.

If the seconds field carries more digits than milli-second order, those will be simply discarded (or in other words, rounded to zero.) For example, for any Calendar value x, 
new Duration("PT10.00099S").getTimeInMills(x) == 10000 new Duration("-PT10.00099S").getTimeInMills(x) == -10000 


 Note that this method uses the addTo(Calendar) method, which may work incorrectly with Duration objects with very large values in its fields. See the addTo(Calendar) method for details. 
Params:
  • startInstant –  The length of a month/year varies. The startInstant is used to disambiguate this variance. Specifically, this method returns the difference between startInstant and startInstant+duration
Throws:
Returns:milliseconds between startInstant and startInstant plus this Duration
/**
     * Returns the length of the duration in milli-seconds.
     *
     * <p>If the seconds field carries more digits than milli-second order,
     * those will be simply discarded (or in other words, rounded to zero.)
     * For example, for any Calendar value {@code x},
     * <pre>
     * {@code new Duration("PT10.00099S").getTimeInMills(x) == 10000}
     * {@code new Duration("-PT10.00099S").getTimeInMills(x) == -10000}
     * </pre>
     *
     * <p>
     * Note that this method uses the {@link #addTo(Calendar)} method,
     * which may work incorrectly with {@code Duration} objects with
     * very large values in its fields. See the {@link #addTo(Calendar)}
     * method for details.
     *
     * @param startInstant
     *      The length of a month/year varies. The {@code startInstant} is
     *      used to disambiguate this variance. Specifically, this method
     *      returns the difference between {@code startInstant} and
     *      {@code startInstant+duration}
     *
     * @return milliseconds between {@code startInstant} and
     *   {@code startInstant} plus this {@code Duration}
     *
     * @throws NullPointerException if {@code startInstant} parameter
     * is null.
     *
     */
    public long getTimeInMillis(final Calendar startInstant) {
        Calendar cal = (Calendar) startInstant.clone();
        addTo(cal);
        return getCalendarTimeInMillis(cal)
                    - getCalendarTimeInMillis(startInstant);
    }

    
Returns the length of the duration in milli-seconds.

If the seconds field carries more digits than milli-second order, those will be simply discarded (or in other words, rounded to zero.) For example, for any Date value x, 
new Duration("PT10.00099S").getTimeInMills(x) == 10000 new Duration("-PT10.00099S").getTimeInMills(x) == -10000 


 Note that this method uses the addTo(Date) method, which may work incorrectly with Duration objects with very large values in its fields. See the addTo(Date) method for details. 
Params:
  • startInstant –  The length of a month/year varies. The startInstant is used to disambiguate this variance. Specifically, this method returns the difference between startInstant and startInstant+duration.
Throws:
See Also:
Returns:milliseconds between startInstant and startInstant plus this Duration
/**
     * Returns the length of the duration in milli-seconds.
     *
     * <p>If the seconds field carries more digits than milli-second order,
     * those will be simply discarded (or in other words, rounded to zero.)
     * For example, for any {@code Date} value {@code x},
     * <pre>
     * {@code new Duration("PT10.00099S").getTimeInMills(x) == 10000}
     * {@code new Duration("-PT10.00099S").getTimeInMills(x) == -10000}
     * </pre>
     *
     * <p>
     * Note that this method uses the {@link #addTo(Date)} method,
     * which may work incorrectly with {@code Duration} objects with
     * very large values in its fields. See the {@link #addTo(Date)}
     * method for details.
     *
     * @param startInstant
     *      The length of a month/year varies. The {@code startInstant} is
     *      used to disambiguate this variance. Specifically, this method
     *      returns the difference between {@code startInstant} and
     *      {@code startInstant+duration}.
     *
     * @throws NullPointerException
     *      If the startInstant parameter is null.
     *
     * @return milliseconds between {@code startInstant} and
     *   {@code startInstant} plus this {@code Duration}
     *
     * @see #getTimeInMillis(Calendar)
     */
    public long getTimeInMillis(final Date startInstant) {
        Calendar cal = new GregorianCalendar();
        cal.setTime(startInstant);
        this.addTo(cal);
        return getCalendarTimeInMillis(cal) - startInstant.getTime();
    }

    
Gets the value of a field. Fields of a duration object may contain arbitrary large value. Therefore this method is designed to return a Number object. In case of YEARS, MONTHS, DAYS, HOURS, and MINUTES, the returned number will be a non-negative integer. In case of seconds, the returned number may be a non-negative decimal value. 
Params:
  • field – 
     one of the six Field constants (YEARS,MONTHS,DAYS,HOURS,
     MINUTES, or SECONDS.)
Throws:
Returns: If the specified field is present, this method returns a non-null non-negative Number object that represents its value. If it is not present, return null. For YEARS, MONTHS, DAYS, HOURS, and MINUTES, this method returns a BigInteger object. For SECONDS, this method returns a BigDecimal.
/**
     * Gets the value of a field.
     *
     * Fields of a duration object may contain arbitrary large value.
     * Therefore this method is designed to return a {@link Number} object.
     *
     * In case of YEARS, MONTHS, DAYS, HOURS, and MINUTES, the returned
     * number will be a non-negative integer. In case of seconds,
     * the returned number may be a non-negative decimal value.
     *
     * @param field
     *      one of the six Field constants (YEARS,MONTHS,DAYS,HOURS,
     *      MINUTES, or SECONDS.)
     * @return
     *      If the specified field is present, this method returns
     *      a non-null non-negative {@link Number} object that
     *      represents its value. If it is not present, return null.
     *      For YEARS, MONTHS, DAYS, HOURS, and MINUTES, this method
     *      returns a {@link java.math.BigInteger} object. For SECONDS, this
     *      method returns a {@link java.math.BigDecimal}.
     *
     * @throws NullPointerException If the {@code field} is {@code null}.
     */
    public abstract Number getField(final DatatypeConstants.Field field);

    
Checks if a field is set.
A field of a duration object may or may not be present.
This method can be used to test if a field is present.

Params:
  • field – 
     one of the six Field constants (YEARS,MONTHS,DAYS,HOURS,
     MINUTES, or SECONDS.)
Throws:
Returns:
     true if the field is present. false if not.
/**
     * Checks if a field is set.
     *
     * A field of a duration object may or may not be present.
     * This method can be used to test if a field is present.
     *
     * @param field
     *      one of the six Field constants (YEARS,MONTHS,DAYS,HOURS,
     *      MINUTES, or SECONDS.)
     * @return
     *      true if the field is present. false if not.
     *
     * @throws NullPointerException
     *      If the field parameter is null.
     */
    public abstract boolean isSet(final DatatypeConstants.Field field);

    
Computes a new duration whose value is this+rhs. 
For example,

"1 day" + "-3 days" = "-2 days"
"1 year" + "1 day" = "1 year and 1 day"
"-(1 hour,50 minutes)" + "-20 minutes" = "-(1 hours,70 minutes)"
"15 hours" + "-3 days" = "-(2 days,9 hours)"
"1 year" + "-1 day" = IllegalStateException



Since there's no way to meaningfully subtract 1 day from 1 month, there are cases where the operation fails in IllegalStateException. 

Formally, the computation is defined as follows.

 Firstly, we can assume that two Durations to be added are both positive without losing generality (i.e., (-X)+Y=Y-X, X+(-Y)=X-Y, (-X)+(-Y)=-(X+Y)) 
 Addition of two positive Durations are simply defined as field by field addition where missing fields are treated as 0. 
 A field of the resulting Duration will be unset if and only if respective fields of two input Durations are unset. 
 Note that lhs.add(rhs) will be always successful if lhs.signum()*rhs.signum()!=-1 or both of them are normalized. 
Params:
  • rhs – Duration to add to this Duration
Throws:
See Also:
Returns:
     non-null valid Duration object.
/**
     * Computes a new duration whose value is {@code this+rhs}.
     *
     * <p>For example,
     * <pre>
     * "1 day" + "-3 days" = "-2 days"
     * "1 year" + "1 day" = "1 year and 1 day"
     * "-(1 hour,50 minutes)" + "-20 minutes" = "-(1 hours,70 minutes)"
     * "15 hours" + "-3 days" = "-(2 days,9 hours)"
     * "1 year" + "-1 day" = IllegalStateException
     * </pre>
     *
     * <p>Since there's no way to meaningfully subtract 1 day from 1 month,
     * there are cases where the operation fails in
     * {@link IllegalStateException}.
     *
     * <p>
     * Formally, the computation is defined as follows.
     * <p>
     * Firstly, we can assume that two {@code Duration}s to be added
     * are both positive without losing generality (i.e.,
     * {@code (-X)+Y=Y-X}, {@code X+(-Y)=X-Y},
     * {@code (-X)+(-Y)=-(X+Y)})
     *
     * <p>
     * Addition of two positive {@code Duration}s are simply defined as
     * field by field addition where missing fields are treated as 0.
     * <p>
     * A field of the resulting {@code Duration} will be unset if and
     * only if respective fields of two input {@code Duration}s are unset.
     * <p>
     * Note that {@code lhs.add(rhs)} will be always successful if
     * {@code lhs.signum()*rhs.signum()!=-1} or both of them are
     * normalized.
     *
     * @param rhs {@code Duration} to add to this {@code Duration}
     *
     * @return
     *      non-null valid Duration object.
     *
     * @throws NullPointerException
     *      If the rhs parameter is null.
     * @throws IllegalStateException
     *      If two durations cannot be meaningfully added. For
     *      example, adding negative one day to one month causes
     *      this exception.
     *
     *
     * @see #subtract(Duration)
     */
    public abstract Duration add(final Duration rhs);

    
Adds this duration to a Calendar object. 
 Calls Calendar.add(int, int) in the order of YEARS, MONTHS, DAYS, HOURS, MINUTES, SECONDS, and MILLISECONDS if those fields are present. Because the Calendar class uses int to hold values, there are cases where this method won't work correctly (for example if values of fields exceed the range of int.) 
 Also, since this duration class is a Gregorian duration, this method will not work correctly if the given Calendar object is based on some other calendar systems. 
 Any fractional parts of this Duration object beyond milliseconds will be simply ignored. For example, if this duration is "P1.23456S", then 1 is added to SECONDS, 234 is added to MILLISECONDS, and the rest will be unused. 
 Note that because Calendar.add(int, int) is using int, Duration with values beyond the range of int in its fields will cause overflow/underflow to the given Calendar. XMLGregorianCalendar.add(Duration) provides the same basic operation as this method while avoiding the overflow/underflow issues. 
Params:
  • calendar – 
     A calendar object whose value will be modified.
Throws:
/**
     * Adds this duration to a {@link Calendar} object.
     *
     * <p>
     * Calls {@link java.util.Calendar#add(int,int)} in the
     * order of YEARS, MONTHS, DAYS, HOURS, MINUTES, SECONDS, and MILLISECONDS
     * if those fields are present. Because the {@link Calendar} class
     * uses int to hold values, there are cases where this method
     * won't work correctly (for example if values of fields
     * exceed the range of int.)
     *
     * <p>
     * Also, since this duration class is a Gregorian duration, this
     * method will not work correctly if the given {@link Calendar}
     * object is based on some other calendar systems.
     *
     * <p>
     * Any fractional parts of this {@code Duration} object
     * beyond milliseconds will be simply ignored. For example, if
     * this duration is "P1.23456S", then 1 is added to SECONDS,
     * 234 is added to MILLISECONDS, and the rest will be unused.
     *
     * <p>
     * Note that because {@link Calendar#add(int, int)} is using
     * {@code int}, {@code Duration} with values beyond the
     * range of {@code int} in its fields
     * will cause overflow/underflow to the given {@link Calendar}.
     * {@link XMLGregorianCalendar#add(Duration)} provides the same
     * basic operation as this method while avoiding
     * the overflow/underflow issues.
     *
     * @param calendar
     *      A calendar object whose value will be modified.
     * @throws NullPointerException
     *      if the calendar parameter is null.
     */
    public abstract void addTo(Calendar calendar);

    
Adds this duration to a Date object. 
 The given date is first converted into a GregorianCalendar, then the duration is added exactly like the addTo(Calendar) method. 
 The updated time instant is then converted back into a Date object and used to update the given Date object. 

This somewhat redundant computation is necessary to unambiguously
determine the duration of months and years.

Params:
  • date – 
     A date object whose value will be modified.
Throws:
/**
     * Adds this duration to a {@link Date} object.
     *
     * <p>
     * The given date is first converted into
     * a {@link java.util.GregorianCalendar}, then the duration
     * is added exactly like the {@link #addTo(Calendar)} method.
     *
     * <p>
     * The updated time instant is then converted back into a
     * {@link Date} object and used to update the given {@link Date} object.
     *
     * <p>
     * This somewhat redundant computation is necessary to unambiguously
     * determine the duration of months and years.
     *
     * @param date
     *      A date object whose value will be modified.
     * @throws NullPointerException
     *      if the date parameter is null.
     */
    public void addTo(Date date) {

        // check data parameter
        if (date == null) {
            throw new NullPointerException(
                "Cannot call "
                + this.getClass().getName()
                + "#addTo(Date date) with date == null."
            );
        }

        Calendar cal = new GregorianCalendar();
        cal.setTime(date);
        this.addTo(cal);
        date.setTime(getCalendarTimeInMillis(cal));
    }

    
Computes a new duration whose value is this-rhs. 
For example:

"1 day" - "-3 days" = "4 days"
"1 year" - "1 day" = IllegalStateException
"-(1 hour,50 minutes)" - "-20 minutes" = "-(1hours,30 minutes)"
"15 hours" - "-3 days" = "3 days and 15 hours"
"1 year" - "-1 day" = "1 year and 1 day"



Since there's no way to meaningfully subtract 1 day from 1 month, there are cases where the operation fails in IllegalStateException. 
Formally the computation is defined as follows. First, we can assume that two Durations are both positive without losing generality. (i.e., (-X)-Y=-(X+Y), X-(-Y)=X+Y, (-X)-(-Y)=-(X-Y)) 
Then two durations are subtracted field by field. If the sign of any non-zero field F is different from the sign of the most significant field, 1 (if F is negative) or -1 (otherwise) will be borrowed from the next bigger unit of F. 
This process is repeated until all the non-zero fields have
the same sign.

If a borrow occurs in the days field (in other words, if the computation needs to borrow 1 or -1 month to compensate days), then the computation fails by throwing an IllegalStateException. 
Params:
  • rhs – Duration to subtract from this Duration.
Throws:
See Also:
Returns:New Duration created from subtracting rhs from this Duration.
/**
     * Computes a new duration whose value is {@code this-rhs}.
     *
     * <p>For example:
     * <pre>
     * "1 day" - "-3 days" = "4 days"
     * "1 year" - "1 day" = IllegalStateException
     * "-(1 hour,50 minutes)" - "-20 minutes" = "-(1hours,30 minutes)"
     * "15 hours" - "-3 days" = "3 days and 15 hours"
     * "1 year" - "-1 day" = "1 year and 1 day"
     * </pre>
     *
     * <p>Since there's no way to meaningfully subtract 1 day from 1 month,
     * there are cases where the operation fails in {@link IllegalStateException}.
     *
     * <p>Formally the computation is defined as follows.
     * First, we can assume that two {@code Duration}s are both positive
     * without losing generality.  (i.e.,
     * {@code (-X)-Y=-(X+Y)}, {@code X-(-Y)=X+Y},
     * {@code (-X)-(-Y)=-(X-Y)})
     *
     * <p>Then two durations are subtracted field by field.
     * If the sign of any non-zero field {@code F} is different from
     * the sign of the most significant field,
     * 1 (if {@code F} is negative) or -1 (otherwise)
     * will be borrowed from the next bigger unit of {@code F}.
     *
     * <p>This process is repeated until all the non-zero fields have
     * the same sign.
     *
     * <p>If a borrow occurs in the days field (in other words, if
     * the computation needs to borrow 1 or -1 month to compensate
     * days), then the computation fails by throwing an
     * {@link IllegalStateException}.
     *
     * @param rhs {@code Duration} to subtract from this {@code Duration}.
     *
     * @return New {@code Duration} created from subtracting {@code rhs} from this {@code Duration}.
     *
     * @throws IllegalStateException
     *      If two durations cannot be meaningfully subtracted. For
     *      example, subtracting one day from one month causes
     *      this exception.
     *
     * @throws NullPointerException
     *      If the rhs parameter is null.
     *
     * @see #add(Duration)
     */
    public Duration subtract(final Duration rhs) {
        return add(rhs.negate());
    }

    
Computes a new duration whose value is factor times longer than the value of this duration. 
This method is provided for the convenience.
It is functionally equivalent to the following code:

multiply(new BigDecimal(String.valueOf(factor)))



Params:
  • factor – Factor times longer of new Duration to create.
See Also:
Returns:New Duration that is factortimes longer than this Duration.
/**
     * Computes a new duration whose value is {@code factor} times
     * longer than the value of this duration.
     *
     * <p>This method is provided for the convenience.
     * It is functionally equivalent to the following code:
     * <pre>
     * multiply(new BigDecimal(String.valueOf(factor)))
     * </pre>
     *
     * @param factor Factor times longer of new {@code Duration} to create.
     *
     * @return New {@code Duration} that is {@code factor}times longer than this {@code Duration}.
     *
     * @see #multiply(BigDecimal)
     */
    public Duration multiply(int factor) {
        return multiply(new BigDecimal(String.valueOf(factor)));
    }

    
Computes a new duration whose value is factor times longer than the value of this duration. 

For example,

"P1M" (1 month) * "12" = "P12M" (12 months)
"PT1M" (1 min) * "0.3" = "PT18S" (18 seconds)
"P1M" (1 month) * "1.5" = IllegalStateException



 Since the Duration class is immutable, this method doesn't change the value of this object. It simply computes a new Duration object and returns it. 
 The operation will be performed field by field with the precision of BigDecimal. Since all the fields except seconds are restricted to hold integers, any fraction produced by the computation will be carried down toward the next lower unit. For example, if you multiply "P1D" (1 day) with "0.5", then it will be 0.5 day, which will be carried down to "PT12H" (12 hours). When fractions of month cannot be meaningfully carried down to days, or year to months, this will cause an IllegalStateException to be thrown. For example if you multiple one month by 0.5. 
 To avoid IllegalStateException, use the normalizeWith(Calendar) method to remove the years and months fields. 
Params:
  • factor – to multiply by
Throws:
Returns: returns a non-null valid Duration object
/**
     * Computes a new duration whose value is {@code factor} times
     * longer than the value of this duration.
     *
     * <p>
     * For example,
     * <pre>
     * "P1M" (1 month) * "12" = "P12M" (12 months)
     * "PT1M" (1 min) * "0.3" = "PT18S" (18 seconds)
     * "P1M" (1 month) * "1.5" = IllegalStateException
     * </pre>
     *
     * <p>
     * Since the {@code Duration} class is immutable, this method
     * doesn't change the value of this object. It simply computes
     * a new Duration object and returns it.
     *
     * <p>
     * The operation will be performed field by field with the precision
     * of {@link BigDecimal}. Since all the fields except seconds are
     * restricted to hold integers,
     * any fraction produced by the computation will be
     * carried down toward the next lower unit. For example,
     * if you multiply "P1D" (1 day) with "0.5", then it will be 0.5 day,
     * which will be carried down to "PT12H" (12 hours).
     * When fractions of month cannot be meaningfully carried down
     * to days, or year to months, this will cause an
     * {@link IllegalStateException} to be thrown.
     * For example if you multiple one month by 0.5.
     *
     * <p>
     * To avoid {@link IllegalStateException}, use
     * the {@link #normalizeWith(Calendar)} method to remove the years
     * and months fields.
     *
     * @param factor to multiply by
     *
     * @return
     *      returns a non-null valid {@code Duration} object
     *
     * @throws IllegalStateException if operation produces fraction in
     * the months field.
     *
     * @throws NullPointerException if the {@code factor} parameter is
     * {@code null}.
     *
     */
    public abstract Duration multiply(final BigDecimal factor);

    
Returns a new Duration object whose value is -this. 
 Since the Duration class is immutable, this method doesn't change the value of this object. It simply computes a new Duration object and returns it. 
Returns: always return a non-null valid Duration object.
/**
     * Returns a new {@code Duration} object whose
     * value is {@code -this}.
     *
     * <p>
     * Since the {@code Duration} class is immutable, this method
     * doesn't change the value of this object. It simply computes
     * a new Duration object and returns it.
     *
     * @return
     *      always return a non-null valid {@code Duration} object.
     */
    public abstract Duration negate();

    
Converts the years and months fields into the days field
by using a specific time instant as the reference point.

For example, duration of one month normalizes to 31 days
given the start time instance "July 8th 2003, 17:40:32".

Formally, the computation is done as follows:

    
 
  1. the given Calendar object is cloned
    2. 
 
  2. the years, months and days fields will be added to the Calendar object by using the Calendar.add(int, int) method
    3. 
 
  3. the difference between the two Calendars in computed in milliseconds and converted to days,
    if a remainder occurs due to Daylight Savings Time, it is discarded
    4. 
 
  4. the computed days, along with the hours, minutes and seconds
     fields of this duration object is used to construct a new
     Duration object.
    5. 



Note that since the Calendar class uses int to hold the value of year and month, this method may produce an unexpected result if this duration object holds a very large value in the years or months fields. 
Params:
  • startTimeInstant – Calendar reference point.
Throws:
Returns:Duration of years and months of this Duration as days.
/**
     * Converts the years and months fields into the days field
     * by using a specific time instant as the reference point.
     *
     * <p>For example, duration of one month normalizes to 31 days
     * given the start time instance "July 8th 2003, 17:40:32".
     *
     * <p>Formally, the computation is done as follows:
     * <ol>
     *  <li>the given Calendar object is cloned</li>
     *  <li>the years, months and days fields will be added to the {@link Calendar} object
     *      by using the {@link Calendar#add(int,int)} method</li>
     *  <li>the difference between the two Calendars in computed in milliseconds and converted to days,
     *     if a remainder occurs due to Daylight Savings Time, it is discarded</li>
     *  <li>the computed days, along with the hours, minutes and seconds
     *      fields of this duration object is used to construct a new
     *      Duration object.</li>
     * </ol>
     *
     * <p>Note that since the Calendar class uses {@code int} to
     * hold the value of year and month, this method may produce
     * an unexpected result if this duration object holds
     * a very large value in the years or months fields.
     *
     * @param startTimeInstant {@code Calendar} reference point.
     *
     * @return {@code Duration} of years and months of this {@code Duration} as days.
     *
     * @throws NullPointerException If the startTimeInstant parameter is null.
     */
    public abstract Duration normalizeWith(final Calendar startTimeInstant);

    
Partial order relation comparison with this Duration instance. 
Comparison result must be in accordance with
W3C XML Schema 1.0 Part 2, Section 3.2.7.6.2,
Order relation on duration.

Return:



Params:
  • duration – to compare
Throws:
  • UnsupportedOperationException – If the underlying implementation
  cannot reasonably process the request, e.g. W3C XML Schema allows for
  arbitrarily large/small/precise values, the request may be beyond the
  implementations capability.
  • NullPointerException – if duration is null.
See Also:
Returns:the relationship between this Duration and duration parameter as DatatypeConstants.LESSER, DatatypeConstants.EQUAL, DatatypeConstants.GREATER or DatatypeConstants.INDETERMINATE.
/**
     * Partial order relation comparison with this {@code Duration} instance.
     *
     * <p>Comparison result must be in accordance with
     * <a href="http://www.w3.org/TR/xmlschema-2/#duration-order">W3C XML Schema 1.0 Part 2, Section 3.2.7.6.2,
     * <i>Order relation on duration</i></a>.
     *
     * <p>Return:
     * <ul>
     *   <li>{@link DatatypeConstants#LESSER} if this {@code Duration} is shorter than {@code duration} parameter</li>
     *   <li>{@link DatatypeConstants#EQUAL} if this {@code Duration} is equal to {@code duration} parameter</li>
     *   <li>{@link DatatypeConstants#GREATER} if this {@code Duration} is longer than {@code duration} parameter</li>
     *   <li>{@link DatatypeConstants#INDETERMINATE} if a conclusive partial order relation cannot be determined</li>
     * </ul>
     *
     * @param duration to compare
     *
     * @return the relationship between {@code this Duration} and {@code duration} parameter as
     *   {@link DatatypeConstants#LESSER}, {@link DatatypeConstants#EQUAL}, {@link DatatypeConstants#GREATER}
     *   or {@link DatatypeConstants#INDETERMINATE}.
     *
     * @throws UnsupportedOperationException If the underlying implementation
     *   cannot reasonably process the request, e.g. W3C XML Schema allows for
     *   arbitrarily large/small/precise values, the request may be beyond the
     *   implementations capability.
     * @throws NullPointerException if {@code duration} is {@code null}.
     *
     * @see #isShorterThan(Duration)
     * @see #isLongerThan(Duration)
     */
    public abstract int compare(final Duration duration);

    
Checks if this duration object is strictly longer than another Duration object. 
Duration X is "longer" than Y if and only if X > Y as defined in the section 3.2.6.2 of the XML Schema 1.0 specification. 
For example, "P1D" (one day) > "PT12H" (12 hours) and "P2Y" (two years) > "P23M" (23 months). 
Params:
  • duration – Duration to test this Duration against.
Throws:
  • UnsupportedOperationException – If the underlying implementation
  cannot reasonably process the request, e.g. W3C XML Schema allows for
  arbitrarily large/small/precise values, the request may be beyond the
  implementations capability.
  • NullPointerException – If duration is null.
See Also:
Returns:
     true if the duration represented by this object
     is longer than the given duration. false otherwise.
/**
     * Checks if this duration object is strictly longer than
     * another {@code Duration} object.
     *
     * <p>Duration X is "longer" than Y if and only if X {@literal >} Y
     * as defined in the section 3.2.6.2 of the XML Schema 1.0
     * specification.
     *
     * <p>For example, "P1D" (one day) {@literal >} "PT12H" (12 hours) and
     * "P2Y" (two years) {@literal >} "P23M" (23 months).
     *
     * @param duration {@code Duration} to test this {@code Duration} against.
     *
     * @throws UnsupportedOperationException If the underlying implementation
     *   cannot reasonably process the request, e.g. W3C XML Schema allows for
     *   arbitrarily large/small/precise values, the request may be beyond the
     *   implementations capability.
     * @throws NullPointerException If {@code duration} is null.
     *
     * @return
     *      true if the duration represented by this object
     *      is longer than the given duration. false otherwise.
     *
     * @see #isShorterThan(Duration)
     * @see #compare(Duration duration)
     */
    public boolean isLongerThan(final Duration duration) {
        return compare(duration) == DatatypeConstants.GREATER;
    }

    
Checks if this duration object is strictly shorter than another Duration object. 
Params:
  • duration – Duration to test this Duration against.
Throws:
  • UnsupportedOperationException – If the underlying implementation
  cannot reasonably process the request, e.g. W3C XML Schema allows for
  arbitrarily large/small/precise values, the request may be beyond the
  implementations capability.
  • NullPointerException – if duration is null.
See Also:
Returns:true if duration parameter is shorter than this Duration, else false.
/**
     * Checks if this duration object is strictly shorter than
     * another {@code Duration} object.
     *
     * @param duration {@code Duration} to test this {@code Duration} against.
     *
     * @return {@code true} if {@code duration} parameter is shorter than this {@code Duration},
     *   else {@code false}.
     *
     * @throws UnsupportedOperationException If the underlying implementation
     *   cannot reasonably process the request, e.g. W3C XML Schema allows for
     *   arbitrarily large/small/precise values, the request may be beyond the
     *   implementations capability.
     * @throws NullPointerException if {@code duration} is null.
     *
     * @see #isLongerThan(Duration duration)
     * @see #compare(Duration duration)
     */
    public boolean isShorterThan(final Duration duration) {
        return compare(duration) == DatatypeConstants.LESSER;
    }

    
Checks if this duration object has the same duration as another Duration object. 
For example, "P1D" (1 day) is equal to "PT24H" (24 hours).

Duration X is equal to Y if and only if time instant
t+X and t+Y are the same for all the test time instants
specified in the section 3.2.6.2 of the XML Schema 1.0
specification.

Note that there are cases where two Durations are "incomparable" to each other, like one month and 30 days. For example, 
!new Duration("P1M").isShorterThan(new Duration("P30D"))
!new Duration("P1M").isLongerThan(new Duration("P30D"))
!new Duration("P1M").equals(new Duration("P30D"))



Params:
  • duration –  The object to compare this Duration against.
Throws:
  • UnsupportedOperationException – If the underlying implementation
  cannot reasonably process the request, e.g. W3C XML Schema allows for
  arbitrarily large/small/precise values, the request may be beyond the
  implementations capability.
See Also:
Returns: true if this duration is the same length as duration. false if duration is null, is not a Duration object, or its length is different from this duration.
/**
     * Checks if this duration object has the same duration
     * as another {@code Duration} object.
     *
     * <p>For example, "P1D" (1 day) is equal to "PT24H" (24 hours).
     *
     * <p>Duration X is equal to Y if and only if time instant
     * t+X and t+Y are the same for all the test time instants
     * specified in the section 3.2.6.2 of the XML Schema 1.0
     * specification.
     *
     * <p>Note that there are cases where two {@code Duration}s are
     * "incomparable" to each other, like one month and 30 days.
     * For example,
     * <pre>
     * !new Duration("P1M").isShorterThan(new Duration("P30D"))
     * !new Duration("P1M").isLongerThan(new Duration("P30D"))
     * !new Duration("P1M").equals(new Duration("P30D"))
     * </pre>
     *
     * @param duration
     *      The object to compare this {@code Duration} against.
     *
     * @return
     *      {@code true} if this duration is the same length as
     *         {@code duration}.
     *      {@code false} if {@code duration} is {@code null},
     *         is not a
     *         {@code Duration} object,
     *         or its length is different from this duration.
     *
     * @throws UnsupportedOperationException If the underlying implementation
     *   cannot reasonably process the request, e.g. W3C XML Schema allows for
     *   arbitrarily large/small/precise values, the request may be beyond the
     *   implementations capability.
     *
     * @see #compare(Duration duration)
     */
    public boolean equals(final Object duration) {

        if (duration == null || !(duration instanceof Duration)) {
            return false;
        }

        return compare((Duration) duration) == DatatypeConstants.EQUAL;
    }

    
Returns a hash code consistent with the definition of the equals method.

See Also:
  • hashCode.hashCode()
/**
     * Returns a hash code consistent with the definition of the equals method.
     *
     * @see Object#hashCode()
     */
    public abstract int hashCode();

    
Returns a String representation of this Duration Object. 
The result is formatted according to the XML Schema 1.0 spec and can be always parsed back later into the equivalent Duration Object by DatatypeFactory.newDuration(String lexicalRepresentation). 
Formally, the following holds for any Duration Object x: 
new Duration(x.toString()).equals(x)



Returns:A non-null valid String representation of this Duration.
/**
     * Returns a {@code String} representation of this {@code Duration Object}.
     *
     * <p>The result is formatted according to the XML Schema 1.0 spec
     * and can be always parsed back later into the
     * equivalent {@code Duration Object} by {@link DatatypeFactory#newDuration(String  lexicalRepresentation)}.
     *
     * <p>Formally, the following holds for any {@code Duration}
     * {@code Object} x:
     * <pre>
     * new Duration(x.toString()).equals(x)
     * </pre>
     *
     * @return A non-{@code null} valid {@code String} representation of this {@code Duration}.
     */
    public String toString() {

        StringBuffer buf = new StringBuffer();

        if (getSign() < 0) {
            buf.append('-');
        }
        buf.append('P');

        BigInteger years = (BigInteger) getField(DatatypeConstants.YEARS);
        if (years != null) {
            buf.append(years + "Y");
        }

        BigInteger months = (BigInteger) getField(DatatypeConstants.MONTHS);
        if (months != null) {
            buf.append(months + "M");
        }

        BigInteger days = (BigInteger) getField(DatatypeConstants.DAYS);
        if (days != null) {
            buf.append(days + "D");
        }

        BigInteger hours = (BigInteger) getField(DatatypeConstants.HOURS);
        BigInteger minutes = (BigInteger) getField(DatatypeConstants.MINUTES);
        BigDecimal seconds = (BigDecimal) getField(DatatypeConstants.SECONDS);
        if (hours != null || minutes != null || seconds != null) {
            buf.append('T');
            if (hours != null) {
                buf.append(hours + "H");
            }
            if (minutes != null) {
                buf.append(minutes + "M");
            }
            if (seconds != null) {
                buf.append(toString(seconds) + "S");
            }
        }

        return buf.toString();
    }

    
Turns BigDecimal to a string representation. 
Due to a behavior change in the BigDecimal.toString() method in JDK1.5, this had to be implemented here. 
Params:
  • bd – BigDecimal to format as a String
Returns: String representation of BigDecimal
/**
     * Turns {@link BigDecimal} to a string representation.
     *
     * <p>Due to a behavior change in the {@link BigDecimal#toString()}
     * method in JDK1.5, this had to be implemented here.
     *
     * @param bd {@code BigDecimal} to format as a {@code String}
     *
     * @return  {@code String} representation of {@code BigDecimal}
     */
    private String toString(BigDecimal bd) {
        String intString = bd.unscaledValue().toString();
        int scale = bd.scale();

        if (scale == 0) {
            return intString;
        }

        /* Insert decimal point */
        StringBuffer buf;
        int insertionPoint = intString.length() - scale;
        if (insertionPoint == 0) { /* Point goes right before intVal */
            return "0." + intString;
        } else if (insertionPoint > 0) { /* Point goes inside intVal */
            buf = new StringBuffer(intString);
            buf.insert(insertionPoint, '.');
        } else { /* We must insert zeros between point and intVal */
            buf = new StringBuffer(3 - insertionPoint + intString.length());
            buf.append("0.");
            for (int i = 0; i < -insertionPoint; i++) {
                buf.append('0');
            }
            buf.append(intString);
        }
        return buf.toString();
    }


    
Calls the Calendar.getTimeInMillis method. Prior to JDK1.4, this method was protected and therefore cannot be invoked directly. 
TODO: In future, this should be replaced by cal.getTimeInMillis(). 
Params:
  • cal – Calendar to get time in milliseconds.
Returns:Milliseconds of cal.
/**
     * Calls the {@link Calendar#getTimeInMillis} method.
     * Prior to JDK1.4, this method was protected and therefore
     * cannot be invoked directly.
     *
     * <p>TODO: In future, this should be replaced by {@code cal.getTimeInMillis()}.
     *
     * @param cal {@code Calendar} to get time in milliseconds.
     *
     * @return Milliseconds of {@code cal}.
     */
    private static long getCalendarTimeInMillis(final Calendar cal) {
        return cal.getTime().getTime();
    }
}