https://openjdk.java.net/ 
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package sun.util.calendar;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.lang.ref.SoftReference;
import java.security.AccessController;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.SimpleTimeZone;
import java.util.TimeZone;


ZoneInfo is an implementation subclass of TimeZone that represents GMT offsets and daylight saving time transitions of a time zone. 
 The daylight saving time transitions are described in the transitions table consisting of a chronological sequence of transitions of GMT offset and/or daylight saving time changes. Since all transitions are represented in UTC, in theory, ZoneInfo can be used with any calendar systems except for the getOffset method that takes Gregorian calendar date fields. 

This table covers transitions from 1900 until 2037 (as of version
1.4), Before 1900, it assumes that there was no daylight saving
time and the getOffset methods always return the getRawOffset value. No Local Mean Time is supported. If a specified date is beyond the transition table and this time zone is supposed to observe daylight saving time in 2037, it delegates operations to a SimpleTimeZone object created using the daylight saving time schedule as of 2037. 
 The date items, transitions, GMT offset(s), etc. are read from a database file. See ZoneInfoFile for details. 
See Also:
Since:1.4
/**
 * <code>ZoneInfo</code> is an implementation subclass of {@link
 * java.util.TimeZone TimeZone} that represents GMT offsets and
 * daylight saving time transitions of a time zone.
 * <p>
 * The daylight saving time transitions are described in the {@link
 * #transitions transitions} table consisting of a chronological
 * sequence of transitions of GMT offset and/or daylight saving time
 * changes. Since all transitions are represented in UTC, in theory,
 * <code>ZoneInfo</code> can be used with any calendar systems except
 * for the {@link #getOffset(int,int,int,int,int,int) getOffset}
 * method that takes Gregorian calendar date fields.
 * <p>
 * This table covers transitions from 1900 until 2037 (as of version
 * 1.4), Before 1900, it assumes that there was no daylight saving
 * time and the <code>getOffset</code> methods always return the
 * {@link #getRawOffset} value. No Local Mean Time is supported. If a
 * specified date is beyond the transition table and this time zone is
 * supposed to observe daylight saving time in 2037, it delegates
 * operations to a {@link java.util.SimpleTimeZone SimpleTimeZone}
 * object created using the daylight saving time schedule as of 2037.
 * <p>
 * The date items, transitions, GMT offset(s), etc. are read from a database
 * file. See {@link ZoneInfoFile} for details.
 * @see java.util.SimpleTimeZone
 * @since 1.4
 */

public class ZoneInfo extends TimeZone {

    private static final int UTC_TIME = 0;
    private static final int STANDARD_TIME = 1;
    private static final int WALL_TIME = 2;

    private static final long OFFSET_MASK = 0x0fL;
    private static final long DST_MASK = 0xf0L;
    private static final int DST_NSHIFT = 4;
    // this bit field is reserved for abbreviation support
    private static final long ABBR_MASK = 0xf00L;
    private static final int TRANSITION_NSHIFT = 12;

    // Flag for supporting JDK backward compatible IDs, such as "EST".
    static final boolean USE_OLDMAPPING;
    static {
      String oldmapping = AccessController.doPrivileged(
          new sun.security.action.GetPropertyAction("sun.timezone.ids.oldmapping", "false")).toLowerCase(Locale.ROOT);
      USE_OLDMAPPING = (oldmapping.equals("yes") || oldmapping.equals("true"));
    }

    // IDs having conflicting data between Olson and JDK 1.1
    static final String[] conflictingIDs = {
        "EST", "MST", "HST"
    };

    private static final CalendarSystem gcal = CalendarSystem.getGregorianCalendar();

    
The raw GMT offset in milliseconds between this zone and GMT.
Negative offsets are to the west of Greenwich.  To obtain local
standard time, add the offset to GMT time.

@serial
/**
     * The raw GMT offset in milliseconds between this zone and GMT.
     * Negative offsets are to the west of Greenwich.  To obtain local
     * <em>standard</em> time, add the offset to GMT time.
     * @serial
     */
    private int rawOffset;

    
Difference in milliseconds from the original GMT offset in case the raw offset value has been modified by calling setRawOffset. The initial value is 0. 
@serial
/**
     * Difference in milliseconds from the original GMT offset in case
     * the raw offset value has been modified by calling {@link
     * #setRawOffset}. The initial value is 0.
     * @serial
     */
    private int rawOffsetDiff = 0;

    
A CRC32 value of all pairs of transition time (in milliseconds
in long) in local time and its GMT offset (in
seconds in int) in the chronological order. Byte
values of each long and int are taken
in the big endian order (i.e., MSB to LSB).

@serial
/**
     * A CRC32 value of all pairs of transition time (in milliseconds
     * in <code>long</code>) in local time and its GMT offset (in
     * seconds in <code>int</code>) in the chronological order. Byte
     * values of each <code>long</code> and <code>int</code> are taken
     * in the big endian order (i.e., MSB to LSB).
     * @serial
     */
    private int checksum;

    
The amount of time in milliseconds saved during daylight saving
time. If useDaylight is false, this value is 0.

@serial
/**
     * The amount of time in milliseconds saved during daylight saving
     * time. If <code>useDaylight</code> is false, this value is 0.
     * @serial
     */
    private int dstSavings;

    
This array describes transitions of GMT offsets of this time
zone, including both raw offset changes and daylight saving
time changes.
A long integer consists of four bit fields.

    

  • The most significant 52-bit field represents transition
time in milliseconds from Gregorian January 1 1970, 00:00:00
GMT.
    • 

  • The next 4-bit field is reserved and must be 0.
    • 

  • The next 4-bit field is an index value to 
offsets[] for the amount of daylight saving at the transition. If this value is zero, it means that no daylight saving, not the index value zero.
    • 

  • The least significant 4-bit field is an index value to offsets[] for total GMT offset at the
transition.
    • 


If this time zone doesn't observe daylight saving time and has
never changed any GMT offsets in the past, this value is null.

@serial
/**
     * This array describes transitions of GMT offsets of this time
     * zone, including both raw offset changes and daylight saving
     * time changes.
     * A long integer consists of four bit fields.
     * <ul>
     * <li>The most significant 52-bit field represents transition
     * time in milliseconds from Gregorian January 1 1970, 00:00:00
     * GMT.</li>
     * <li>The next 4-bit field is reserved and must be 0.</li>
     * <li>The next 4-bit field is an index value to {@link #offsets
     * offsets[]} for the amount of daylight saving at the
     * transition. If this value is zero, it means that no daylight
     * saving, not the index value zero.</li>
     * <li>The least significant 4-bit field is an index value to
     * {@link #offsets offsets[]} for <em>total</em> GMT offset at the
     * transition.</li>
     * </ul>
     * If this time zone doesn't observe daylight saving time and has
     * never changed any GMT offsets in the past, this value is null.
     * @serial
     */
    private long[] transitions;

    
This array holds all unique offset values in
milliseconds. Index values to this array are stored in the
transitions array elements.

@serial
/**
     * This array holds all unique offset values in
     * milliseconds. Index values to this array are stored in the
     * transitions array elements.
     * @serial
     */
    private int[] offsets;

    
SimpleTimeZone parameter values. It has to have either 8 for the
11-argument SimpleTimeZone constructor or 10 for the
13-argument SimpleTimeZone constructor parameters. 
@serial
/**
     * SimpleTimeZone parameter values. It has to have either 8 for
     * {@link java.util.SimpleTimeZone#SimpleTimeZone(int, String,
     * int, int , int , int , int , int , int , int , int) the
     * 11-argument SimpleTimeZone constructor} or 10 for {@link
     * java.util.SimpleTimeZone#SimpleTimeZone(int, String, int, int,
     * int , int , int , int , int , int , int, int, int) the
     * 13-argument SimpleTimeZone constructor} parameters.
     * @serial
     */
    private int[] simpleTimeZoneParams;

    
True if the raw GMT offset value would change after the time
zone data has been generated; false, otherwise. The default
value is false.

@serial
/**
     * True if the raw GMT offset value would change after the time
     * zone data has been generated; false, otherwise. The default
     * value is false.
     * @serial
     */
    private boolean willGMTOffsetChange = false;

    
True if the object has been modified after its instantiation.

/**
     * True if the object has been modified after its instantiation.
     */
    transient private boolean dirty = false;

    private static final long serialVersionUID = 2653134537216586139L;

    
A constructor.

/**
     * A constructor.
     */
    public ZoneInfo() {
    }

    
A Constructor for CustomID.

/**
     * A Constructor for CustomID.
     */
    public ZoneInfo(String ID, int rawOffset) {
        this(ID, rawOffset, 0, 0, null, null, null, false);
    }

    
Constructs a ZoneInfo instance.

Params:
  • ID – time zone name
  • rawOffset – GMT offset in milliseconds
  • dstSavings – daylight saving value in milliseconds or 0
(zero) if this time zone doesn't observe Daylight Saving Time.
  • checksum – CRC32 value with all transitions table entry
values
  • transitions – transition table
  • offsets – offset value table
  • simpleTimeZoneParams – parameter values for constructing
SimpleTimeZone
  • willGMTOffsetChange – the value of willGMTOffsetChange
/**
     * Constructs a ZoneInfo instance.
     *
     * @param ID time zone name
     * @param rawOffset GMT offset in milliseconds
     * @param dstSavings daylight saving value in milliseconds or 0
     * (zero) if this time zone doesn't observe Daylight Saving Time.
     * @param checksum CRC32 value with all transitions table entry
     * values
     * @param transitions transition table
     * @param offsets offset value table
     * @param simpleTimeZoneParams parameter values for constructing
     * SimpleTimeZone
     * @param willGMTOffsetChange the value of willGMTOffsetChange
     */
    ZoneInfo(String ID,
             int rawOffset,
             int dstSavings,
             int checksum,
             long[] transitions,
             int[] offsets,
             int[] simpleTimeZoneParams,
             boolean willGMTOffsetChange) {
        setID(ID);
        this.rawOffset = rawOffset;
        this.dstSavings = dstSavings;
        this.checksum = checksum;
        this.transitions = transitions;
        this.offsets = offsets;
        this.simpleTimeZoneParams = simpleTimeZoneParams;
        this.willGMTOffsetChange = willGMTOffsetChange;
    }

    
Returns the difference in milliseconds between local time and UTC
of given time, taking into account both the raw offset and the
effect of daylight savings.

Params:
  • date – the milliseconds in UTC
Returns:the milliseconds to add to UTC to get local wall time
/**
     * Returns the difference in milliseconds between local time and UTC
     * of given time, taking into account both the raw offset and the
     * effect of daylight savings.
     *
     * @param date the milliseconds in UTC
     * @return the milliseconds to add to UTC to get local wall time
     */
    public int getOffset(long date) {
        return getOffsets(date, null, UTC_TIME);
    }

    public int getOffsets(long utc, int[] offsets) {
        return getOffsets(utc, offsets, UTC_TIME);
    }

    public int getOffsetsByStandard(long standard, int[] offsets) {
        return getOffsets(standard, offsets, STANDARD_TIME);
    }

    public int getOffsetsByWall(long wall, int[] offsets) {
        return getOffsets(wall, offsets, WALL_TIME);
    }

    private int getOffsets(long date, int[] offsets, int type) {
        // if dst is never observed, there is no transition.
        if (transitions == null) {
            int offset = getLastRawOffset();
            if (offsets != null) {
                offsets[0] = offset;
                offsets[1] = 0;
            }
            return offset;
        }

        date -= rawOffsetDiff;
        int index = getTransitionIndex(date, type);

        // prior to the transition table, returns the raw offset.
        // FIXME: should support LMT.
        if (index < 0) {
            int offset = getLastRawOffset();
            if (offsets != null) {
                offsets[0] = offset;
                offsets[1] = 0;
            }
            return offset;
        }

        if (index < transitions.length) {
            long val = transitions[index];
            int offset = this.offsets[(int)(val & OFFSET_MASK)] + rawOffsetDiff;
            if (offsets != null) {
                int dst = (int)((val >>> DST_NSHIFT) & 0xfL);
                int save = (dst == 0) ? 0 : this.offsets[dst];
                offsets[0] = offset - save;
                offsets[1] = save;
            }
            return offset;
        }

        // beyond the transitions, delegate to SimpleTimeZone if there
        // is a rule; otherwise, return rawOffset.
        SimpleTimeZone tz = getLastRule();
        if (tz != null) {
            int rawoffset = tz.getRawOffset();
            long msec = date;
            if (type != UTC_TIME) {
                msec -= rawOffset;
            }
            int dstoffset = tz.getOffset(msec) - rawOffset;

            // Check if it's in a standard-to-daylight transition.
            if (dstoffset > 0 && tz.getOffset(msec - dstoffset) == rawoffset) {
                dstoffset = 0;
            }

            if (offsets != null) {
                offsets[0] = rawoffset;
                offsets[1] = dstoffset;
            }
            return rawoffset + dstoffset;
        }
        int offset = getLastRawOffset();
        if (offsets != null) {
            offsets[0] = offset;
            offsets[1] = 0;
        }
        return offset;
    }

    private int getTransitionIndex(long date, int type) {
        int low = 0;
        int high = transitions.length - 1;

        while (low <= high) {
            int mid = (low + high) / 2;
            long val = transitions[mid];
            long midVal = val >> TRANSITION_NSHIFT; // sign extended
            if (type != UTC_TIME) {
                midVal += offsets[(int)(val & OFFSET_MASK)]; // wall time
            }
            if (type == STANDARD_TIME) {
                int dstIndex = (int)((val >>> DST_NSHIFT) & 0xfL);
                if (dstIndex != 0) {
                    midVal -= offsets[dstIndex]; // make it standard time
                }
            }

            if (midVal < date) {
                low = mid + 1;
            } else if (midVal > date) {
                high = mid - 1;
            } else {
                return mid;
            }
        }

        // if beyond the transitions, returns that index.
        if (low >= transitions.length) {
            return low;
        }
        return low - 1;
    }

   
Returns the difference in milliseconds between local time and
UTC, taking into account both the raw offset and the effect of
daylight savings, for the specified date and time.  This method
assumes that the start and end month are distinct.  This method
assumes a Gregorian calendar for calculations.


Note: In general, clients should use Calendar.get(ZONE_OFFSET) + Calendar.get(DST_OFFSET) instead of calling this method.

Params:
  • era –       The era of the given date. The value must be either
                 GregorianCalendar.AD or GregorianCalendar.BC.
  • year –      The year in the given date.
  • month –     The month in the given date. Month is 0-based. e.g.,
                 0 for January.
  • day –       The day-in-month of the given date.
  • dayOfWeek – The day-of-week of the given date.
  • millis –    The milliseconds in day in standard local time.
Returns:The milliseconds to add to UTC to get local time.
/**
     * Returns the difference in milliseconds between local time and
     * UTC, taking into account both the raw offset and the effect of
     * daylight savings, for the specified date and time.  This method
     * assumes that the start and end month are distinct.  This method
     * assumes a Gregorian calendar for calculations.
     * <p>
     * <em>Note: In general, clients should use
     * {@link Calendar#ZONE_OFFSET Calendar.get(ZONE_OFFSET)} +
     * {@link Calendar#DST_OFFSET Calendar.get(DST_OFFSET)}
     * instead of calling this method.</em>
     *
     * @param era       The era of the given date. The value must be either
     *                  GregorianCalendar.AD or GregorianCalendar.BC.
     * @param year      The year in the given date.
     * @param month     The month in the given date. Month is 0-based. e.g.,
     *                  0 for January.
     * @param day       The day-in-month of the given date.
     * @param dayOfWeek The day-of-week of the given date.
     * @param millis    The milliseconds in day in <em>standard</em> local time.
     * @return The milliseconds to add to UTC to get local time.
     */
    public int getOffset(int era, int year, int month, int day,
                         int dayOfWeek, int milliseconds) {
        if (milliseconds < 0 || milliseconds >= AbstractCalendar.DAY_IN_MILLIS) {
            throw new IllegalArgumentException();
        }

        if (era == java.util.GregorianCalendar.BC) { // BC
            year = 1 - year;
        } else if (era != java.util.GregorianCalendar.AD) {
            throw new IllegalArgumentException();
        }

        CalendarDate date = gcal.newCalendarDate(null);
        date.setDate(year, month + 1, day);
        if (gcal.validate(date) == false) {
            throw new IllegalArgumentException();
        }

        // bug-for-bug compatible argument checking
        if (dayOfWeek < java.util.GregorianCalendar.SUNDAY
            || dayOfWeek > java.util.GregorianCalendar.SATURDAY) {
            throw new IllegalArgumentException();
        }

        if (transitions == null) {
            return getLastRawOffset();
        }

        long dateInMillis = gcal.getTime(date) + milliseconds;
        dateInMillis -= (long) rawOffset; // make it UTC
        return getOffsets(dateInMillis, null, UTC_TIME);
    }

    
Sets the base time zone offset from GMT. This operation
modifies all the transitions of this ZoneInfo object, including
historical ones, if applicable.

Params:
  • offsetMillis – the base time zone offset to GMT.
See Also:
  • getRawOffset
/**
     * Sets the base time zone offset from GMT. This operation
     * modifies all the transitions of this ZoneInfo object, including
     * historical ones, if applicable.
     *
     * @param offsetMillis the base time zone offset to GMT.
     * @see getRawOffset
     */
    public synchronized void setRawOffset(int offsetMillis) {
        if (offsetMillis == rawOffset + rawOffsetDiff) {
            return;
        }
        rawOffsetDiff = offsetMillis - rawOffset;
        if (lastRule != null) {
            lastRule.setRawOffset(offsetMillis);
        }
        dirty = true;
    }

    
Returns the GMT offset of the current date. This GMT offset
value is not modified during Daylight Saving Time.

Returns:the GMT offset value in milliseconds to add to UTC time
to get local standard time
/**
     * Returns the GMT offset of the current date. This GMT offset
     * value is not modified during Daylight Saving Time.
     *
     * @return the GMT offset value in milliseconds to add to UTC time
     * to get local standard time
     */
    public int getRawOffset() {
        if (!willGMTOffsetChange) {
            return rawOffset + rawOffsetDiff;
        }

        int[] offsets = new int[2];
        getOffsets(System.currentTimeMillis(), offsets, UTC_TIME);
        return offsets[0];
    }

    public boolean isDirty() {
        return dirty;
    }

    private int getLastRawOffset() {
        return rawOffset + rawOffsetDiff;
    }

    
Queries if this time zone uses Daylight Saving Time in the last known rule.

/**
     * Queries if this time zone uses Daylight Saving Time in the last known rule.
     */
    public boolean useDaylightTime() {
        return (simpleTimeZoneParams != null);
    }

    @Override
    public boolean observesDaylightTime() {
        if (simpleTimeZoneParams != null) {
            return true;
        }
        if (transitions == null) {
            return false;
        }

        // Look up the transition table to see if it's in DST right
        // now or if there's any standard-to-daylight transition at
        // any future.
        long utc = System.currentTimeMillis() - rawOffsetDiff;
        int index = getTransitionIndex(utc, UTC_TIME);

        // before transitions in the transition table
        if (index < 0) {
            return false;
        }

        // the time is in the table range.
        for (int i = index; i < transitions.length; i++) {
            if ((transitions[i] & DST_MASK) != 0) {
                return true;
            }
        }
        // No further DST is observed.
        return false;
    }

    
Queries if the specified date is in Daylight Saving Time.

/**
     * Queries if the specified date is in Daylight Saving Time.
     */
    public boolean inDaylightTime(Date date) {
        if (date == null) {
            throw new NullPointerException();
        }

        if (transitions == null) {
            return false;
        }

        long utc = date.getTime() - rawOffsetDiff;
        int index = getTransitionIndex(utc, UTC_TIME);

        // before transitions in the transition table
        if (index < 0) {
            return false;
        }

        // the time is in the table range.
        if (index < transitions.length) {
            return (transitions[index] & DST_MASK) != 0;
        }

        // beyond the transition table
        SimpleTimeZone tz = getLastRule();
        if (tz != null) {
            return tz.inDaylightTime(date);
        }
        return false;
    }

    
Returns the amount of time in milliseconds that the clock is advanced
during daylight saving time is in effect in its last daylight saving time rule.

Returns:the number of milliseconds the time is advanced with respect to
standard time when daylight saving time is in effect.
/**
     * Returns the amount of time in milliseconds that the clock is advanced
     * during daylight saving time is in effect in its last daylight saving time rule.
     *
     * @return the number of milliseconds the time is advanced with respect to
     * standard time when daylight saving time is in effect.
     */
    public int getDSTSavings() {
        return dstSavings;
    }

//    /**
//     * @return the last year in the transition table or -1 if this
//     * time zone doesn't observe any daylight saving time.
//     */
//    public int getMaxTransitionYear() {
//      if (transitions == null) {
//          return -1;
//      }
//      long val = transitions[transitions.length - 1];
//      int offset = this.offsets[(int)(val & OFFSET_MASK)] + rawOffsetDiff;
//      val = (val >> TRANSITION_NSHIFT) + offset;
//      CalendarDate lastDate = Gregorian.getCalendarDate(val);
//      return lastDate.getYear();
//    }

    
Returns a string representation of this time zone.

Returns:the string
/**
     * Returns a string representation of this time zone.
     * @return the string
     */
    public String toString() {
        return getClass().getName() +
            "[id=\"" + getID() + "\"" +
            ",offset=" + getLastRawOffset() +
            ",dstSavings=" + dstSavings +
            ",useDaylight=" + useDaylightTime() +
            ",transitions=" + ((transitions != null) ? transitions.length : 0) +
            ",lastRule=" + (lastRule == null ? getLastRuleInstance() : lastRule) +
            "]";
    }

    
Gets all available IDs supported in the Java run-time.

Returns:an array of time zone IDs.
/**
     * Gets all available IDs supported in the Java run-time.
     *
     * @return an array of time zone IDs.
     */
    public static String[] getAvailableIDs() {
        List<String> idList = ZoneInfoFile.getZoneIDs();
        List<String> excluded = ZoneInfoFile.getExcludedZones();
        if (excluded != null) {
            // List all zones from the idList and excluded lists
            List<String> list = new ArrayList<>(idList.size() + excluded.size());
            list.addAll(idList);
            list.addAll(excluded);
            idList = list;
        }
        String[] ids = new String[idList.size()];
        return idList.toArray(ids);
    }

    
Gets all available IDs that have the same value as the
specified raw GMT offset.

Params:
  • rawOffset – the GMT offset in milliseconds. This
value should not include any daylight saving time.
Returns:an array of time zone IDs.
/**
     * Gets all available IDs that have the same value as the
     * specified raw GMT offset.
     *
     * @param rawOffset the GMT offset in milliseconds. This
     * value should not include any daylight saving time.
     *
     * @return an array of time zone IDs.
     */
    public static String[] getAvailableIDs(int rawOffset) {
        String[] result;
        List<String> matched = new ArrayList<>();
        List<String> IDs = ZoneInfoFile.getZoneIDs();
        int[] rawOffsets = ZoneInfoFile.getRawOffsets();

    loop:
        for (int index = 0; index < rawOffsets.length; index++) {
            if (rawOffsets[index] == rawOffset) {
                byte[] indices = ZoneInfoFile.getRawOffsetIndices();
                for (int i = 0; i < indices.length; i++) {
                    if (indices[i] == index) {
                        matched.add(IDs.get(i++));
                        while (i < indices.length && indices[i] == index) {
                            matched.add(IDs.get(i++));
                        }
                        break loop;
                    }
                }
            }
        }

        // We need to add any zones from the excluded zone list that
        // currently have the same GMT offset as the specified
        // rawOffset. The zones returned by this method may not be
        // correct as of return to the caller if any GMT offset
        // transition is happening during this GMT offset checking...
        List<String> excluded = ZoneInfoFile.getExcludedZones();
        if (excluded != null) {
            for (String id : excluded) {
                TimeZone zi = getTimeZone(id);
                if (zi != null && zi.getRawOffset() == rawOffset) {
                    matched.add(id);
                }
            }
        }

        result = new String[matched.size()];
        matched.toArray(result);
        return result;
    }

    
Gets the ZoneInfo for the given ID.

Params:
  • ID – the ID for a ZoneInfo. See TimeZone for detail.
Returns:the specified ZoneInfo object, or null if there is no
time zone of the ID.
/**
     * Gets the ZoneInfo for the given ID.
     *
     * @param ID the ID for a ZoneInfo. See TimeZone for detail.
     *
     * @return the specified ZoneInfo object, or null if there is no
     * time zone of the ID.
     */
    public static TimeZone getTimeZone(String ID) {
        String givenID = null;

        /*
         * If old JDK compatibility is specified, get the old alias
         * name.
         */
        if (USE_OLDMAPPING) {
            String compatibleID = TzIDOldMapping.MAP.get(ID);
            if (compatibleID != null) {
                givenID = ID;
                ID = compatibleID;
            }
        }

        ZoneInfo zi = ZoneInfoFile.getZoneInfo(ID);
        if (zi == null) {
            // if we can't create an object for the ID, try aliases.
            try {
                Map<String, String> map = getAliasTable();
                String alias = ID;
                while ((alias = map.get(alias)) != null) {
                    zi = ZoneInfoFile.getZoneInfo(alias);
                    if (zi != null) {
                        zi.setID(ID);
                        zi = ZoneInfoFile.addToCache(ID, zi);
                        zi = (ZoneInfo) zi.clone();
                        break;
                    }
                }
            } catch (Exception e) {
                // ignore exceptions
            }
        }

        if (givenID != null && zi != null) {
            zi.setID(givenID);
        }
        return zi;
    }

    private transient SimpleTimeZone lastRule;

    
Returns a SimpleTimeZone object representing the last GMT
offset and DST schedule or null if this time zone doesn't
observe DST.

/**
     * Returns a SimpleTimeZone object representing the last GMT
     * offset and DST schedule or null if this time zone doesn't
     * observe DST.
     */
    private synchronized SimpleTimeZone getLastRule() {
        if (lastRule == null) {
            lastRule = getLastRuleInstance();
        }
        return lastRule;
    }

    
Returns a SimpleTimeZone object that represents the last
known daylight saving time rules.

Returns:a SimpleTimeZone object or null if this time zone
doesn't observe DST.
/**
     * Returns a SimpleTimeZone object that represents the last
     * known daylight saving time rules.
     *
     * @return a SimpleTimeZone object or null if this time zone
     * doesn't observe DST.
     */
    public SimpleTimeZone getLastRuleInstance() {
        if (simpleTimeZoneParams == null) {
            return null;
        }
        if (simpleTimeZoneParams.length == 10) {
            return new SimpleTimeZone(getLastRawOffset(), getID(),
                                      simpleTimeZoneParams[0],
                                      simpleTimeZoneParams[1],
                                      simpleTimeZoneParams[2],
                                      simpleTimeZoneParams[3],
                                      simpleTimeZoneParams[4],
                                      simpleTimeZoneParams[5],
                                      simpleTimeZoneParams[6],
                                      simpleTimeZoneParams[7],
                                      simpleTimeZoneParams[8],
                                      simpleTimeZoneParams[9],
                                      dstSavings);
        }
        return new SimpleTimeZone(getLastRawOffset(), getID(),
                                  simpleTimeZoneParams[0],
                                  simpleTimeZoneParams[1],
                                  simpleTimeZoneParams[2],
                                  simpleTimeZoneParams[3],
                                  simpleTimeZoneParams[4],
                                  simpleTimeZoneParams[5],
                                  simpleTimeZoneParams[6],
                                  simpleTimeZoneParams[7],
                                  dstSavings);
    }

    
Returns a copy of this ZoneInfo.

/**
     * Returns a copy of this <code>ZoneInfo</code>.
     */
    public Object clone() {
        ZoneInfo zi = (ZoneInfo) super.clone();
        zi.lastRule = null;
        return zi;
    }

    
Returns a hash code value calculated from the GMT offset and
transitions.

Returns:a hash code of this time zone
/**
     * Returns a hash code value calculated from the GMT offset and
     * transitions.
     * @return a hash code of this time zone
     */
    public int hashCode() {
        return getLastRawOffset() ^ checksum;
    }

    
Compares the equity of two ZoneInfo objects.

Params:
  • obj – the object to be compared with
Returns:true if given object is same as this ZoneInfo object,
false otherwise.
/**
     * Compares the equity of two ZoneInfo objects.
     *
     * @param obj the object to be compared with
     * @return true if given object is same as this ZoneInfo object,
     * false otherwise.
     */
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (!(obj instanceof ZoneInfo)) {
            return false;
        }
        ZoneInfo that = (ZoneInfo) obj;
        return (getID().equals(that.getID())
                && (getLastRawOffset() == that.getLastRawOffset())
                && (checksum == that.checksum));
    }

    
Returns true if this zone has the same raw GMT offset value and
transition table as another zone info. If the specified
TimeZone object is not a ZoneInfo instance, this method returns
true if the specified TimeZone object has the same raw GMT
offset value with no daylight saving time.

Params:
  • other – the ZoneInfo object to be compared with
Returns:true if the given TimeZone has the same
GMT offset and transition information; false, otherwise.
/**
     * Returns true if this zone has the same raw GMT offset value and
     * transition table as another zone info. If the specified
     * TimeZone object is not a ZoneInfo instance, this method returns
     * true if the specified TimeZone object has the same raw GMT
     * offset value with no daylight saving time.
     *
     * @param other the ZoneInfo object to be compared with
     * @return true if the given <code>TimeZone</code> has the same
     * GMT offset and transition information; false, otherwise.
     */
    public boolean hasSameRules(TimeZone other) {
        if (this == other) {
            return true;
        }
        if (other == null) {
            return false;
        }
        if (!(other instanceof ZoneInfo)) {
            if (getRawOffset() != other.getRawOffset()) {
                return false;
            }
            // if both have the same raw offset and neither observes
            // DST, they have the same rule.
            if ((transitions == null)
                && (useDaylightTime() == false)
                && (other.useDaylightTime() == false)) {
                return true;
            }
            return false;
        }
        if (getLastRawOffset() != ((ZoneInfo)other).getLastRawOffset()) {
            return false;
        }
        return (checksum == ((ZoneInfo)other).checksum);
    }

    private static SoftReference<Map<String, String>> aliasTable;

    static Map<String, String> getCachedAliasTable() {
        Map<String, String> aliases = null;

        SoftReference<Map<String, String>> cache = aliasTable;
        if (cache != null) {
            aliases = cache.get();
        }
        return aliases;
    }

    
Returns a Map from alias time zone IDs to their standard
time zone IDs.

Returns:the Map that holds the mappings from alias time zone IDs
   to their standard time zone IDs, or null if
   ZoneInfoMappings file is not available.
/**
     * Returns a Map from alias time zone IDs to their standard
     * time zone IDs.
     *
     * @return the Map that holds the mappings from alias time zone IDs
     *    to their standard time zone IDs, or null if
     *    <code>ZoneInfoMappings</code> file is not available.
     */
    public synchronized static Map<String, String> getAliasTable() {
        Map<String, String> aliases = getCachedAliasTable();
        if (aliases == null) {
            aliases = ZoneInfoFile.getZoneAliases();
            if (aliases != null) {
                if (!USE_OLDMAPPING) {
                    // Remove the conflicting IDs from the alias table.
                    for (String key : conflictingIDs) {
                        aliases.remove(key);
                    }
                }
                aliasTable = new SoftReference<Map<String, String>>(aliases);
            }
        }
        return aliases;
    }

    private void readObject(ObjectInputStream stream)
            throws IOException, ClassNotFoundException {
        stream.defaultReadObject();
        // We don't know how this object from 1.4.x or earlier has
        // been mutated. So it should always be marked as `dirty'.
        dirty = true;
    }
}