/*
 
* Copyright (c) 1996, 2014, 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.
 
*
 
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/*
 
* (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.security.AccessController;
import java.security.PrivilegedAction;
import java.time.ZoneId;
import sun.security.action.GetPropertyAction;
import sun.util.calendar.ZoneInfo;
import sun.util.calendar.ZoneInfoFile;
import sun.util.locale.provider.TimeZoneNameUtility;

/**
 
* <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".
 
*
 
* <h3>Three-letter time zone IDs</h3>
 
*
 
* 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."
     
*
 

     
* @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."
     
*
 

     
* @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 offsets 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:
     
* <blockquote><pre>
     
* getDisplayName(false,
 
,
     
*
                
Locale.getDefault({@link Locale.Category#DISPLAY}))
     
* </pre></blockquote>
     
*
     
* @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:
     
* <blockquote><pre>
     
* getDisplayName(false,
 
, locale)
     
* </pre></blockquote>
     
*
     
* @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:
     
* <blockquote><pre>
     
* getDisplayName(daylight, style,
     
*
                
Locale.getDefault({@link Locale.Category#DISPLAY}))
     
* </pre></blockquote>
     
*
     
* @param daylight {@code true} specifying a Daylight Saving Time name, or
     
*
                 
{@code false} specifying a Standard Time name
     
* @param style either
 
 
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
 
 
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 name = TimeZoneNameUtility.retrieveDisplayName(id, daylight, style, locale);
        
if (name != null) {
            
return name;
        
}

        
if (id.startsWith("GMT") && id.length() > 3) {
            
char sign = id.charAt(3);
            
if (sign == '+' || sign == '-') {
                
return id;
            
}
        
}
        
int offset = getRawOffset();
        
if (daylight) {
            
offset += getDSTSavings();
        
}
        
return ZoneInfoFile.toCustomID(offset);
    
}

    
private static String[] getDisplayNames(String id, Locale locale) {
        
return TimeZoneNameUtility.retrieveDisplayNames(id, locale);
    
}

    
/**
     
* 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
 

     
* 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
 

     
* 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 #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);
    
}

    
/**
     
* Gets the {@code TimeZone} for the given {@code zoneId}.
     
*
     
* @param zoneId a {@link ZoneId} from which the time zone ID is obtained
     
* @return the specified {@code TimeZone}, or the GMT zone if the given ID
     
*
         
cannot be understood.
     
* @throws NullPointerException if {@code zoneId} is {@code null}
     
* @since 1.8
     
*/

    
public static TimeZone getTimeZone(ZoneId zoneId) {
        
String tzid = zoneId.getId(); // throws an NPE if null
        
char c = tzid.charAt(0);
        
if (c == '+' || c == '-') {
            
tzid = "GMT" + tzid;
        
} else if (c == 'Z' && tzid.length() == 1) {
            
tzid = "UTC";
        
}
        
return getTimeZone(tzid, true);
    
}

    
/**
     
* Converts this {@code TimeZone} object to a {@code ZoneId}.
     
*
     
* @return a {@code ZoneId} representing the same time zone as this
     
*
         
{@code TimeZone}
     
* @since 1.8
     
*/

    
public ZoneId toZoneId() {
        
String id = getID();
        
if (ZoneInfoFile.useOldMapping() && id.length() == 3) {
            
if ("EST".equals(id))
                
return ZoneId.of("America/New_York");
            
if ("MST".equals(id))
                
return ZoneId.of("America/Denver");
            
if ("HST".equals(id))
                
return ZoneId.of("America/Honolulu");
        
}
        
return ZoneId.of(id, ZoneId.SHORT_IDS);
    
}

    
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.
     
*
 

     
*/

    
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);

    
/**
     
* 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} of the Java virtual machine. If the
     
* cached default {@code TimeZone} is available, its clone is returned.
     
* Otherwise, the method takes the following steps to determine the default
     
* time zone.
     
*
     
* <ul>
     
* <li>Use the {@code user.timezone} property value as the default
     
* time zone ID if it's available.</li>
     
* <li>Detect the platform time zone ID. The source of the
     
* platform time zone and ID mapping may vary with implementation.</li>
     
* <li>Use {@code GMT} as the last resort if the given or detected
     
* time zone ID is unknown.</li>
     
* </ul>
     
*
     
* <p>The default {@code TimeZone} created from the ID is cached,
     
* and its clone is returned. The {@code user.timezone} property
     
* value is set to the ID upon return.
     
*
     
* @return the default {@code TimeZone}
     
* @see #setDefault(TimeZone)
     
*/

    
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 = 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;
        
// 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.isEmpty()) {
            
String javaHome = AccessController.doPrivileged(
                    
new GetPropertyAction("java.home"));
            
try {
                
zoneID = getSystemTimeZoneID(javaHome);
                
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<Void>() {
            
@Override
                
public Void run() {
                    
System.setProperty("user.timezone", id);
                    
return null;
                
}
            
});

        
defaultTimeZone = tz;
        
return tz;
    
}

    
/**
     
* Sets the {@code TimeZone} that is returned by the {@code getDefault}
     
* method. {@code zone} is cached. If {@code zone} is null, the cached
     
* default {@code TimeZone} is cleared. This method doesn't change the value
     
* of the {@code user.timezone} property.
     
*
     
* @param zone the new default {@code TimeZone}, or null
     
* @throws SecurityException if the security manager's {@code checkPermission}
     
*
                           
denies {@code PropertyPermission("user.timezone",
     
*
                           
"write")}
     
* @see #getDefault
     
* @see PropertyPermission
     
*/

    
public static void setDefault(TimeZone zone)
    
{
        
SecurityManager sm = System.getSecurityManager();
        
if (sm != null) {
            
sm.checkPermission(new PropertyPermission
                               
("user.timezone", "write"));
        
}
        
defaultTimeZone = 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(e);
        
}
    
}

    
/**
     
* 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;

    
static final String
         
GMT_ID
        
= "GMT";
    
private static final int
    
GMT_ID_LENGTH = 3;

    
// a static TimeZone we can reference if no AppContext is in place
    
private static volatile TimeZone mainAppContextDefault;

    
/**
     
* 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;
    
}
}