/*

  * Copyright (c) 1996, 2011, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * 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

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  */

 /*

  * (C) Copyright Taligent, Inc. 1996 - All Rights Reserved

  * (C) Copyright IBM Corp. 1996 - 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.Serializable;

 import java.lang.ref.SoftReference;

 import java.security.AccessController;

 import java.security.PrivilegedAction;

 import java.util.concurrent.ConcurrentHashMap;

 import sun.security.action.GetPropertyAction;

 import sun.util.TimeZoneNameUtility;

 import sun.util.calendar.ZoneInfo;

 import sun.util.calendar.ZoneInfoFile;

 /**

  * <code>TimeZone</code> represents a time zone offset, and also figures out daylight

  * savings.

  *

  * <p>

  * Typically, you get a <code>TimeZone</code> using <code>getDefault</code>

  * which creates a <code>TimeZone</code> based on the time zone where the program

  * is running. For example, for a program running in Japan, <code>getDefault</code>

  * creates a <code>TimeZone</code> object based on Japanese Standard Time.

  *

  * <p>

  * You can also get a <code>TimeZone</code> using <code>getTimeZone</code>

  * along with a time zone ID. For instance, the time zone ID for the

  * U.S. Pacific Time zone is "America/Los_Angeles". So, you can get a

  * U.S. Pacific Time <code>TimeZone</code> object with:

  * <blockquote><pre>

  * TimeZone tz = TimeZone.getTimeZone("America/Los_Angeles");

  * </pre></blockquote>

  * You can use the <code>getAvailableIDs</code> method to iterate through

  * all the supported time zone IDs. You can then choose a

  * supported ID to get a <code>TimeZone</code>.

  * If the time zone you want is not represented by one of the

  * supported IDs, then a custom time zone ID can be specified to

  * produce a TimeZone. The syntax of a custom time zone ID is:

  *

  * <blockquote><pre>

  * <a name="CustomID"><i>CustomID:</i></a>

  *         <code>GMT</code> <i>Sign</i> <i>Hours</i> <code>:</code> <i>Minutes</i>

  *         <code>GMT</code> <i>Sign</i> <i>Hours</i> <i>Minutes</i>

  *         <code>GMT</code> <i>Sign</i> <i>Hours</i>

  * <i>Sign:</i> one of

  *         <code>+ -</code>

  * <i>Hours:</i>

  *         <i>Digit</i>

  *         <i>Digit</i> <i>Digit</i>

  * <i>Minutes:</i>

  *         <i>Digit</i> <i>Digit</i>

  * <i>Digit:</i> one of

  *         <code>0 1 2 3 4 5 6 7 8 9</code>

  * </pre></blockquote>

  *

  * <i>Hours</i> must be between 0 to 23 and <i>Minutes</i> must be

  * between 00 to 59.  For example, "GMT+10" and "GMT+0010" mean ten

  * hours and ten minutes ahead of GMT, respectively.

  * <p>

  * The format is locale independent and digits must be taken from the

  * Basic Latin block of the Unicode standard. No daylight saving time

  * transition schedule can be specified with a custom time zone ID. If

  * the specified string doesn't match the syntax, <code>"GMT"</code>

  * is used.

  * <p>

  * When creating a <code>TimeZone</code>, the specified custom time

  * zone ID is normalized in the following syntax:

  * <blockquote><pre>

  * <a name="NormalizedCustomID"><i>NormalizedCustomID:</i></a>

  *         <code>GMT</code> <i>Sign</i> <i>TwoDigitHours</i> <code>:</code> <i>Minutes</i>

  * <i>Sign:</i> one of

  *         <code>+ -</code>

  * <i>TwoDigitHours:</i>

  *         <i>Digit</i> <i>Digit</i>

  * <i>Minutes:</i>

  *         <i>Digit</i> <i>Digit</i>

  * <i>Digit:</i> one of

  *         <code>0 1 2 3 4 5 6 7 8 9</code>

  * </pre></blockquote>

  * For example, TimeZone.getTimeZone("GMT-8").getID() returns "GMT-08:00".

  *

  * <h4>Three-letter time zone IDs</h4>

  *

  * For compatibility with JDK 1.1.x, some other three-letter time zone IDs

  * (such as "PST", "CTT", "AST") are also supported. However, <strong>their

  * use is deprecated</strong> because the same abbreviation is often used

  * for multiple time zones (for example, "CST" could be U.S. "Central Standard

  * Time" and "China Standard Time"), and the Java platform can then only

  * recognize one of them.

  *

  *

  * @see          Calendar

  * @see          GregorianCalendar

  * @see          SimpleTimeZone

  * @author       Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu

  * @since        JDK1.1

  */

 abstract public class TimeZone implements Serializable, Cloneable {

     /**

      * Sole constructor.  (For invocation by subclass constructors, typically

      * implicit.)

      */

     public TimeZone() {

     }

     /**

      * A style specifier for <code>getDisplayName()</code> indicating

      * a short name, such as "PST."

      * @see #LONG

      * @since 1.2

      */

     public static final int SHORT = 0;

     /**

      * A style specifier for <code>getDisplayName()</code> indicating

      * a long name, such as "Pacific Standard Time."

      * @see #SHORT

      * @since 1.2

      */

     public static final int LONG  = 1;

     // Constants used internally; unit is milliseconds

     private static final int ONE_MINUTE = 60*1000;

     private static final int ONE_HOUR   = 60*ONE_MINUTE;

     private static final int ONE_DAY    = 24*ONE_HOUR;

     // Proclaim serialization compatibility with JDK 1.1

     static final long serialVersionUID = 3581463369166924961L;

     /**

      * Gets the time zone offset, for current date, modified in case of

      * daylight savings. This is the offset to add to UTC to get local time.

      * <p>

      * This method returns a historically correct offset if an

      * underlying <code>TimeZone</code> implementation subclass

      * supports historical Daylight Saving Time schedule and GMT

      * offset changes.

      *

      * @param era the era of the given date.

      * @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 milliseconds the milliseconds in day in <em>standard</em>

      * local time.

      *

      * @return the offset in milliseconds to add to GMT to get local time.

      *

      * @see Calendar#ZONE_OFFSET

      * @see Calendar#DST_OFFSET

      */

     public abstract int getOffset(int era, int year, int month, int day,

                                   int dayOfWeek, int milliseconds);

     /**

      * Returns the offset of this time zone from UTC at the specified

      * date. If Daylight Saving Time is in effect at the specified

      * date, the offset value is adjusted with the amount of daylight

      * saving.

      * <p>

      * This method returns a historically correct offset value if an

      * underlying TimeZone implementation subclass supports historical

      * Daylight Saving Time schedule and GMT offset changes.

      *

      * @param date the date represented in milliseconds since January 1, 1970 00:00:00 GMT

      * @return the amount of time in milliseconds to add to UTC to get local time.

      *

      * @see Calendar#ZONE_OFFSET

      * @see Calendar#DST_OFFSET

      * @since 1.4

      */

     public int getOffset(long date) {

         if (inDaylightTime(new Date(date))) {

             return getRawOffset() + getDSTSavings();

         }

         return getRawOffset();

     }

     /**

      * Gets the raw GMT offset and the amount of daylight saving of this

      * time zone at the given time.

      * @param date the milliseconds (since January 1, 1970,

      * 00:00:00.000 GMT) at which the time zone offset and daylight

      * saving amount are found

      * @param offset an array of int where the raw GMT offset

      * (offset[0]) and daylight saving amount (offset[1]) are stored,

      * or null if those values are not needed. The method assumes that

      * the length of the given array is two or larger.

      * @return the total amount of the raw GMT offset and daylight

      * saving at the specified date.

      *

      * @see Calendar#ZONE_OFFSET

      * @see Calendar#DST_OFFSET

      */

     int getOffsets(long date, int[] offsets) {

         int rawoffset = getRawOffset();

         int dstoffset = 0;

         if (inDaylightTime(new Date(date))) {

             dstoffset = getDSTSavings();

         }

         if (offsets != null) {

             offsets[0] = rawoffset;

             offsets[1] = dstoffset;

         }

         return rawoffset + dstoffset;

     }

     /**

      * Sets the base time zone offset to GMT.

      * This is the offset to add to UTC to get local time.

      * <p>

      * If an underlying <code>TimeZone</code> implementation subclass

      * supports historical GMT offset changes, the specified GMT

      * offset is set as the latest GMT offset and the difference from

      * the known latest GMT offset value is used to adjust all

      * historical GMT offset values.

      *

      * @param offsetMillis the given base time zone offset to GMT.

      */

     abstract public void setRawOffset(int offsetMillis);

     /**

      * Returns the amount of time in milliseconds to add to UTC to get

      * standard time in this time zone. Because this value is not

      * affected by daylight saving time, it is called <I>raw

      * offset</I>.

      * <p>

      * If an underlying <code>TimeZone</code> implementation subclass

      * supports historical GMT offset changes, the method returns the

      * raw offset value of the current date. In Honolulu, for example,

      * its raw offset changed from GMT-10:30 to GMT-10:00 in 1947, and

      * this method always returns -36000000 milliseconds (i.e., -10

      * hours).

      *

      * @return the amount of raw offset time in milliseconds to add to UTC.

      * @see Calendar#ZONE_OFFSET

      */

     public abstract int getRawOffset();

     /**

      * Gets the ID of this time zone.

      * @return the ID of this time zone.

      */

     public String getID()

     {

         return ID;

     }

     /**

      * Sets the time zone ID. This does not change any other data in

      * the time zone object.

      * @param ID the new time zone ID.

      */

     public void setID(String ID)

     {

         if (ID == null) {

             throw new NullPointerException();

         }

         this.ID = ID;

     }

     /**

      * Returns a long standard time name of this {@code TimeZone} suitable for

      * presentation to the user in the default locale.

      *

      * <p>This method is equivalent to:

      * <pre><blockquote>

      * getDisplayName(false, {@link #LONG},

      *                Locale.getDefault({@link Locale.Category#DISPLAY}))

      * </blockquote></pre>

      *

      * @return the human-readable name of this time zone in the default locale.

      * @since 1.2

      * @see #getDisplayName(boolean, int, Locale)

      * @see Locale#getDefault(Locale.Category)

      * @see Locale.Category

      */

     public final String getDisplayName() {

         return getDisplayName(false, LONG,

                               Locale.getDefault(Locale.Category.DISPLAY));

     }

     /**

      * Returns a long standard time name of this {@code TimeZone} suitable for

      * presentation to the user in the specified {@code locale}.

      *

      * <p>This method is equivalent to:

      * <pre><blockquote>

      * getDisplayName(false, {@link #LONG}, locale)

      * </blockquote></pre>

      *

      * @param locale the locale in which to supply the display name.

      * @return the human-readable name of this time zone in the given locale.

      * @exception NullPointerException if {@code locale} is {@code null}.

      * @since 1.2

      * @see #getDisplayName(boolean, int, Locale)

      */

     public final String getDisplayName(Locale locale) {

         return getDisplayName(false, LONG, locale);

     }

     /**

      * Returns a name in the specified {@code style} of this {@code TimeZone}

      * suitable for presentation to the user in the default locale. If the

      * specified {@code daylight} is {@code true}, a Daylight Saving Time name

      * is returned (even if this {@code TimeZone} doesn't observe Daylight Saving

      * Time). Otherwise, a Standard Time name is returned.

      *

      * <p>This method is equivalent to:

      * <pre><blockquote>

      * getDisplayName(daylight, style,

      *                Locale.getDefault({@link Locale.Category#DISPLAY}))

      * </blockquote></pre>

      *

      * @param daylight {@code true} specifying a Daylight Saving Time name, or

      *                 {@code false} specifying a Standard Time name

      * @param style either {@link #LONG} or {@link #SHORT}

      * @return the human-readable name of this time zone in the default locale.

      * @exception IllegalArgumentException if {@code style} is invalid.

      * @since 1.2

      * @see #getDisplayName(boolean, int, Locale)

      * @see Locale#getDefault(Locale.Category)

      * @see Locale.Category

      * @see java.text.DateFormatSymbols#getZoneStrings()

      */

     public final String getDisplayName(boolean daylight, int style) {

         return getDisplayName(daylight, style,

                               Locale.getDefault(Locale.Category.DISPLAY));

     }

     /**

      * Returns a name in the specified {@code style} of this {@code TimeZone}

      * suitable for presentation to the user in the specified {@code

      * locale}. If the specified {@code daylight} is {@code true}, a Daylight

      * Saving Time name is returned (even if this {@code TimeZone} doesn't

      * observe Daylight Saving Time). Otherwise, a Standard Time name is

      * returned.

      *

      * <p>When looking up a time zone name, the {@linkplain

      * ResourceBundle.Control#getCandidateLocales(String,Locale) default

      * <code>Locale</code> search path of <code>ResourceBundle</code>} derived

      * from the specified {@code locale} is used. (No {@linkplain

      * ResourceBundle.Control#getFallbackLocale(String,Locale) fallback

      * <code>Locale</code>} search is performed.) If a time zone name in any

      * {@code Locale} of the search path, including {@link Locale#ROOT}, is

      * found, the name is returned. Otherwise, a string in the

      * <a href="#NormalizedCustomID">normalized custom ID format</a> is returned.

      *

      * @param daylight {@code true} specifying a Daylight Saving Time name, or

      *                 {@code false} specifying a Standard Time name

      * @param style either {@link #LONG} or {@link #SHORT}

      * @param locale   the locale in which to supply the display name.

      * @return the human-readable name of this time zone in the given locale.

      * @exception IllegalArgumentException if {@code style} is invalid.

      * @exception NullPointerException if {@code locale} is {@code null}.

      * @since 1.2

      * @see java.text.DateFormatSymbols#getZoneStrings()

      */

     public String getDisplayName(boolean daylight, int style, Locale locale) {

         if (style != SHORT && style != LONG) {

             throw new IllegalArgumentException("Illegal style: " + style);

         }

         String id = getID();

         String[] names = getDisplayNames(id, locale);

         if (names == null) {

             if (id.startsWith("GMT")) {

                 char sign = id.charAt(3);

                 if (sign == '+' || sign == '-') {

                     return id;

                 }

             }

             int offset = getRawOffset();

             if (daylight) {

                 offset += getDSTSavings();

             }

             return ZoneInfoFile.toCustomID(offset);

         }

         int index = daylight ? 3 : 1;

         if (style == SHORT) {

             index++;

         }

         return names[index];

     }

     private static class DisplayNames {

         // Cache for managing display names per timezone per locale

         // The structure is:

         //   Map(key=id, value=SoftReference(Map(key=locale, value=displaynames)))

         private static final Map<String, SoftReference<Map<Locale, String[]>>> CACHE =

             new ConcurrentHashMap<String, SoftReference<Map<Locale, String[]>>>();

     }

     private static final String[] getDisplayNames(String id, Locale locale) {

         Map<String, SoftReference<Map<Locale, String[]>>> displayNames = DisplayNames.CACHE;

         SoftReference<Map<Locale, String[]>> ref = displayNames.get(id);

         if (ref != null) {

             Map<Locale, String[]> perLocale = ref.get();

             if (perLocale != null) {

                 String[] names = perLocale.get(locale);

                 if (names != null) {

                     return names;

                 }

                 names = TimeZoneNameUtility.retrieveDisplayNames(id, locale);

                 if (names != null) {

                     perLocale.put(locale, names);

                 }

                 return names;

             }

         }

         String[] names = TimeZoneNameUtility.retrieveDisplayNames(id, locale);

         if (names != null) {

             Map<Locale, String[]> perLocale = new ConcurrentHashMap<Locale, String[]>();

             perLocale.put(locale, names);

             ref = new SoftReference<Map<Locale, String[]>>(perLocale);

             displayNames.put(id, ref);

         }

         return names;

     }

     /**

      * Returns the amount of time to be added to local standard time

      * to get local wall clock time.

      *

      * <p>The default implementation returns 3600000 milliseconds

      * (i.e., one hour) if a call to {@link #useDaylightTime()}

      * returns {@code true}. Otherwise, 0 (zero) is returned.

      *

      * <p>If an underlying {@code TimeZone} implementation subclass

      * supports historical and future Daylight Saving Time schedule

      * changes, this method returns the amount of saving time of the

      * last known Daylight Saving Time rule that can be a future

      * prediction.

      *

      * <p>If the amount of saving time at any given time stamp is

      * required, construct a {@link Calendar} with this {@code

      * TimeZone} and the time stamp, and call {@link Calendar#get(int)

      * Calendar.get}{@code (}{@link Calendar#DST_OFFSET}{@code )}.

      *

      * @return the amount of saving time in milliseconds

      * @since 1.4

      * @see #inDaylightTime(Date)

      * @see #getOffset(long)

      * @see #getOffset(int,int,int,int,int,int)

      * @see Calendar#ZONE_OFFSET

      */

     public int getDSTSavings() {

         if (useDaylightTime()) {

             return 3600000;

         }

         return 0;

     }

     /**

      * Queries if this {@code TimeZone} uses Daylight Saving Time.

      *

      * <p>If an underlying {@code TimeZone} implementation subclass

      * supports historical and future Daylight Saving Time schedule

      * changes, this method refers to the last known Daylight Saving Time

      * rule that can be a future prediction and may not be the same as

      * the current rule. Consider calling {@link #observesDaylightTime()}

      * if the current rule should also be taken into account.

      *

      * @return {@code true} if this {@code TimeZone} uses Daylight Saving Time,

      *         {@code false}, otherwise.

      * @see #inDaylightTime(Date)

      * @see Calendar#DST_OFFSET

      */

     public abstract boolean useDaylightTime();

     /**

      * Returns {@code true} if this {@code TimeZone} is currently in

      * Daylight Saving Time, or if a transition from Standard Time to

      * Daylight Saving Time occurs at any future time.

      *

      * <p>The default implementation returns {@code true} if

      * {@code useDaylightTime()} or {@code inDaylightTime(new Date())}

      * returns {@code true}.

      *

      * @return {@code true} if this {@code TimeZone} is currently in

      * Daylight Saving Time, or if a transition from Standard Time to

      * Daylight Saving Time occurs at any future time; {@code false}

      * otherwise.

      * @since 1.7

      * @see #useDaylightTime()

      * @see #inDaylightTime(Date)

      * @see Calendar#DST_OFFSET

      */

     public boolean observesDaylightTime() {

         return useDaylightTime() || inDaylightTime(new Date());

     }

     /**

      * Queries if the given {@code date} is in Daylight Saving Time in

      * this time zone.

      *

      * @param date the given Date.

      * @return {@code true} if the given date is in Daylight Saving Time,

      *         {@code false}, otherwise.

      */

     abstract public boolean inDaylightTime(Date date);

     /**

      * Gets the <code>TimeZone</code> for the given ID.

      *

      * @param ID the ID for a <code>TimeZone</code>, either an abbreviation

      * such as "PST", a full name such as "America/Los_Angeles", or a custom

      * ID such as "GMT-8:00". Note that the support of abbreviations is

      * for JDK 1.1.x compatibility only and full names should be used.

      *

      * @return the specified <code>TimeZone</code>, or the GMT zone if the given ID

      * cannot be understood.

      */

     public static synchronized TimeZone getTimeZone(String ID) {

         return getTimeZone(ID, true);

     }

     private static TimeZone getTimeZone(String ID, boolean fallback) {

         TimeZone tz = ZoneInfo.getTimeZone(ID);

         if (tz == null) {

             tz = parseCustomTimeZone(ID);

             if (tz == null && fallback) {

                 tz = new ZoneInfo(GMT_ID, 0);

             }

         }

         return tz;

     }

     /**

      * Gets the available IDs according to the given time zone offset in milliseconds.

      *

      * @param rawOffset the given time zone GMT offset in milliseconds.

      * @return an array of IDs, where the time zone for that ID has

      * the specified GMT offset. For example, "America/Phoenix" and "America/Denver"

      * both have GMT-07:00, but differ in daylight saving behavior.

      * @see #getRawOffset()

      */

     public static synchronized String[] getAvailableIDs(int rawOffset) {

         return ZoneInfo.getAvailableIDs(rawOffset);

     }

     /**

      * Gets all the available IDs supported.

      * @return an array of IDs.

      */

     public static synchronized String[] getAvailableIDs() {

         return ZoneInfo.getAvailableIDs();

     }

     /**

      * Gets the platform defined TimeZone ID.

      **/

     private static native String getSystemTimeZoneID(String javaHome,

                                                      String country);

     /**

      * Gets the custom time zone ID based on the GMT offset of the

      * platform. (e.g., "GMT+08:00")

      */

     private static native String getSystemGMTOffsetID();

     /**

      * Gets the default <code>TimeZone</code> for this host.

      * The source of the default <code>TimeZone</code>

      * may vary with implementation.

      * @return a default <code>TimeZone</code>.

      * @see #setDefault

      */

     public static TimeZone getDefault() {

         return (TimeZone) getDefaultRef().clone();

     }

     /**

      * Returns the reference to the default TimeZone object. This

      * method doesn't create a clone.

      */

     static TimeZone getDefaultRef() {

         TimeZone defaultZone = defaultZoneTL.get();

         if (defaultZone == null) {

             defaultZone = defaultTimeZone;

             if (defaultZone == null) {

                 // Need to initialize the default time zone.

                 defaultZone = setDefaultZone();

                 assert defaultZone != null;

             }

         }

         // Don't clone here.

         return defaultZone;

     }

     private static synchronized TimeZone setDefaultZone() {

         TimeZone tz = null;

         // get the time zone ID from the system properties

         String zoneID = AccessController.doPrivileged(

                 new GetPropertyAction("user.timezone"));

         // if the time zone ID is not set (yet), perform the

         // platform to Java time zone ID mapping.

         if (zoneID == null || zoneID.equals("")) {

             String country = AccessController.doPrivileged(

                     new GetPropertyAction("user.country"));

             String javaHome = AccessController.doPrivileged(

                     new GetPropertyAction("java.home"));

             try {

                 zoneID = getSystemTimeZoneID(javaHome, country);

                 if (zoneID == null) {

                     zoneID = GMT_ID;

                 }

             } catch (NullPointerException e) {

                 zoneID = GMT_ID;

             }

         }

         // Get the time zone for zoneID. But not fall back to

         // "GMT" here.

         tz = getTimeZone(zoneID, false);

         if (tz == null) {

             // If the given zone ID is unknown in Java, try to

             // get the GMT-offset-based time zone ID,

             // a.k.a. custom time zone ID (e.g., "GMT-08:00").

             String gmtOffsetID = getSystemGMTOffsetID();

             if (gmtOffsetID != null) {

                 zoneID = gmtOffsetID;

             }

             tz = getTimeZone(zoneID, true);

         }

         assert tz != null;

         final String id = zoneID;

         AccessController.doPrivileged(new PrivilegedAction<Object>() {

                 public Object run() {

                     System.setProperty("user.timezone", id);

                     return null;

                 }

             });

         defaultTimeZone = tz;

         return tz;

     }

     private static boolean hasPermission() {

         boolean hasPermission = true;

         SecurityManager sm = System.getSecurityManager();

         if (sm != null) {

             try {

                 sm.checkPermission(new PropertyPermission

                                    ("user.timezone", "write"));

             } catch (SecurityException e) {

                 hasPermission = false;

             }

         }

         return hasPermission;

     }

     /**

      * Sets the <code>TimeZone</code> that is

      * returned by the <code>getDefault</code> method.  If <code>zone</code>

      * is null, reset the default to the value it had originally when the

      * VM first started.

      * @param zone the new default time zone

      * @see #getDefault

      */

     public static void setDefault(TimeZone zone)

     {

         if (hasPermission()) {

             synchronized (TimeZone.class) {

                 defaultTimeZone = zone;

                 defaultZoneTL.set(null);

             }

         } else {

             defaultZoneTL.set(zone);

         }

     }

     /**

      * Returns true if this zone has the same rule and offset as another zone.

      * That is, if this zone differs only in ID, if at all.  Returns false

      * if the other zone is null.

      * @param other the <code>TimeZone</code> object to be compared with

      * @return true if the other zone is not null and is the same as this one,

      * with the possible exception of the ID

      * @since 1.2

      */

     public boolean hasSameRules(TimeZone other) {

         return other != null && getRawOffset() == other.getRawOffset() &&

             useDaylightTime() == other.useDaylightTime();

     }

     /**

      * Creates a copy of this <code>TimeZone</code>.

      *

      * @return a clone of this <code>TimeZone</code>

      */

     public Object clone()

     {

         try {

             TimeZone other = (TimeZone) super.clone();

             other.ID = ID;

             return other;

         } catch (CloneNotSupportedException e) {

             throw new InternalError();

         }

     }

     /**

      * The null constant as a TimeZone.

      */

     static final TimeZone NO_TIMEZONE = null;

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

     /**

      * The string identifier of this <code>TimeZone</code>.  This is a

      * programmatic identifier used internally to look up <code>TimeZone</code>

      * objects from the system table and also to map them to their localized

      * display names.  <code>ID</code> values are unique in the system

      * table but may not be for dynamically created zones.

      * @serial

      */

     private String           ID;

     private static volatile TimeZone defaultTimeZone;

     private static final InheritableThreadLocal<TimeZone> defaultZoneTL

                                         = new InheritableThreadLocal<TimeZone>();

     static final String         GMT_ID        = "GMT";

     private static final int    GMT_ID_LENGTH = 3;

     /**

      * Parses a custom time zone identifier and returns a corresponding zone.

      * This method doesn't support the RFC 822 time zone format. (e.g., +hhmm)

      *

      * @param id a string of the <a href="#CustomID">custom ID form</a>.

      * @return a newly created TimeZone with the given offset and

      * no daylight saving time, or null if the id cannot be parsed.

      */

     private static final TimeZone parseCustomTimeZone(String id) {

         int length;

         // Error if the length of id isn't long enough or id doesn't

         // start with "GMT".

         if ((length = id.length()) < (GMT_ID_LENGTH + 2) ||

             id.indexOf(GMT_ID) != 0) {

             return null;

         }

         ZoneInfo zi;

         // First, we try to find it in the cache with the given

         // id. Even the id is not normalized, the returned ZoneInfo

         // should have its normalized id.

         zi = ZoneInfoFile.getZoneInfo(id);

         if (zi != null) {

             return zi;

         }

         int index = GMT_ID_LENGTH;

         boolean negative = false;

         char c = id.charAt(index++);

         if (c == '-') {

             negative = true;

         } else if (c != '+') {

             return null;

         }

         int hours = 0;

         int num = 0;

         int countDelim = 0;

         int len = 0;

         while (index < length) {

             c = id.charAt(index++);

             if (c == ':') {

                 if (countDelim > 0) {

                     return null;

                 }

                 if (len > 2) {

                     return null;

                 }

                 hours = num;

                 countDelim++;

                 num = 0;

                 len = 0;

                 continue;

             }

             if (c < '0' || c > '9') {

                 return null;

             }

             num = num * 10 + (c - '0');

             len++;

         }

         if (index != length) {

             return null;

         }

         if (countDelim == 0) {

             if (len <= 2) {

                 hours = num;

                 num = 0;

             } else {

                 hours = num / 100;

                 num %= 100;

             }

         } else {

             if (len != 2) {

                 return null;

             }

         }

         if (hours > 23 || num > 59) {

             return null;

         }

         int gmtOffset =  (hours * 60 + num) * 60 * 1000;

         if (gmtOffset == 0) {

             zi = ZoneInfoFile.getZoneInfo(GMT_ID);

             if (negative) {

                 zi.setID("GMT-00:00");

             } else {

                 zi.setID("GMT+00:00");

             }

         } else {

             zi = ZoneInfoFile.getCustomTimeZone(id, negative ? -gmtOffset : gmtOffset);

         }

         return zi;

     }

 }