- java.lang.Object
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- java.util.TimeZone
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- All Implemented Interfaces:
Serializable,Cloneable
- Direct Known Subclasses:
SimpleTimeZone
public abstract class TimeZone extends Object implements Serializable, Cloneable
TimeZonerepresents a time zone offset, and also figures out daylight savings.Typically, you get a
TimeZoneusinggetDefaultwhich creates aTimeZonebased on the time zone where the program is running. For example, for a program running in Japan,getDefaultcreates aTimeZoneobject based on Japanese Standard Time.You can also get a
TimeZoneusinggetTimeZonealong 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 TimeTimeZoneobject with:
You can use theTimeZone tz = TimeZone.getTimeZone("America/Los_Angeles");getAvailableIDsmethod to iterate through all the supported time zone IDs. You can then choose a supported ID to get aTimeZone. 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:
Hours must be between 0 to 23 and Minutes must be between 00 to 59. For example, "GMT+10" and "GMT+0010" mean ten hours and ten minutes ahead of GMT, respectively.CustomID:
GMTSign Hours:MinutesGMTSign Hours MinutesGMTSign Hours Sign: one of+ -Hours: Digit Digit Digit Minutes: Digit Digit Digit: one of0 1 2 3 4 5 6 7 8 9The 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,
"GMT"is used.When creating a
TimeZone, the specified custom time zone ID is normalized in the following syntax:
For example, TimeZone.getTimeZone("GMT-8").getID() returns "GMT-08:00".NormalizedCustomID:
GMTSign TwoDigitHours:Minutes Sign: one of+ -TwoDigitHours: Digit Digit Minutes: Digit Digit Digit: one of0 1 2 3 4 5 6 7 8 9Three-letter time zone IDs
For compatibility with JDK 1.1.x, some other three-letter time zone IDs (such as "PST", "CTT", "AST") are also supported. However, their use is deprecated 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.- Since:
- 1.1
- See Also:
Calendar,GregorianCalendar,SimpleTimeZone, Serialized Form
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Constructor Summary
Constructors Constructor Description TimeZone()Sole constructor.
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description Objectclone()Creates a copy of thisTimeZone.static String[]getAvailableIDs()Gets all the available IDs supported.static String[]getAvailableIDs(int rawOffset)Gets the available IDs according to the given time zone offset in milliseconds.static TimeZonegetDefault()Gets the defaultTimeZoneof the Java virtual machine.StringgetDisplayName()Returns a long standard time name of thisTimeZonesuitable for presentation to the user in the default locale.StringgetDisplayName(boolean daylight, int style)Returns a name in the specifiedstyleof thisTimeZonesuitable for presentation to the user in the default locale.StringgetDisplayName(boolean daylight, int style, Locale locale)Returns a name in the specifiedstyleof thisTimeZonesuitable for presentation to the user in the specifiedlocale.StringgetDisplayName(Locale locale)Returns a long standard time name of thisTimeZonesuitable for presentation to the user in the specifiedlocale.intgetDSTSavings()Returns the amount of time to be added to local standard time to get local wall clock time.StringgetID()Gets the ID of this time zone.abstract intgetOffset(int era, int year, int month, int day, int dayOfWeek, int milliseconds)Gets the time zone offset, for current date, modified in case of daylight savings.intgetOffset(long date)Returns the offset of this time zone from UTC at the specified date.abstract intgetRawOffset()Returns the amount of time in milliseconds to add to UTC to get standard time in this time zone.static TimeZonegetTimeZone(String ID)Gets theTimeZonefor the given ID.static TimeZonegetTimeZone(ZoneId zoneId)Gets theTimeZonefor the givenzoneId.booleanhasSameRules(TimeZone other)Returns true if this zone has the same rule and offset as another zone.abstract booleaninDaylightTime(Date date)Queries if the givendateis in Daylight Saving Time in this time zone.booleanobservesDaylightTime()Returnstrueif thisTimeZoneis currently in Daylight Saving Time, or if a transition from Standard Time to Daylight Saving Time occurs at any future time.static voidsetDefault(TimeZone zone)Sets theTimeZonethat is returned by thegetDefaultmethod.voidsetID(String ID)Sets the time zone ID.abstract voidsetRawOffset(int offsetMillis)Sets the base time zone offset to GMT.ZoneIdtoZoneId()Converts thisTimeZoneobject to aZoneId.abstract booleanuseDaylightTime()Queries if thisTimeZoneuses Daylight Saving Time.
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Field Detail
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SHORT
public static final int SHORT
A style specifier forgetDisplayName()indicating a short name, such as "PST."- Since:
- 1.2
- See Also:
LONG, Constant Field Values
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LONG
public static final int LONG
A style specifier forgetDisplayName()indicating a long name, such as "Pacific Standard Time."- Since:
- 1.2
- See Also:
SHORT, Constant Field Values
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Method Detail
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getOffset
public abstract int getOffset(int era, int year, int month, int day, int dayOfWeek, int milliseconds)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.This method returns a historically correct offset if an underlying
TimeZoneimplementation subclass supports historical Daylight Saving Time schedule and GMT offset changes.- Parameters:
era- the era of the given date.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.milliseconds- the milliseconds in day in standard local time.- Returns:
- the offset in milliseconds to add to GMT to get local time.
- See Also:
Calendar.ZONE_OFFSET,Calendar.DST_OFFSET
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getOffset
public int getOffset(long date)
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.This method returns a historically correct offset value if an underlying TimeZone implementation subclass supports historical Daylight Saving Time schedule and GMT offset changes.
- Parameters:
date- the date represented in milliseconds since January 1, 1970 00:00:00 GMT- Returns:
- the amount of time in milliseconds to add to UTC to get local time.
- Since:
- 1.4
- See Also:
Calendar.ZONE_OFFSET,Calendar.DST_OFFSET
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setRawOffset
public abstract void setRawOffset(int offsetMillis)
Sets the base time zone offset to GMT. This is the offset to add to UTC to get local time.If an underlying
TimeZoneimplementation 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.- Parameters:
offsetMillis- the given base time zone offset to GMT.
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getRawOffset
public abstract int getRawOffset()
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 raw offset.If an underlying
TimeZoneimplementation 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).- Returns:
- the amount of raw offset time in milliseconds to add to UTC.
- See Also:
Calendar.ZONE_OFFSET
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getID
public String getID()
Gets the ID of this time zone.- Returns:
- the ID of this time zone.
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setID
public void setID(String ID)
Sets the time zone ID. This does not change any other data in the time zone object.- Parameters:
ID- the new time zone ID.
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getDisplayName
public final String getDisplayName()
Returns a long standard time name of thisTimeZonesuitable for presentation to the user in the default locale.This method is equivalent to:
getDisplayName(false,
LONG, Locale.getDefault(Locale.Category.DISPLAY))- Returns:
- the human-readable name of this time zone in the default locale.
- Since:
- 1.2
- See Also:
getDisplayName(boolean, int, Locale),Locale.getDefault(Locale.Category),Locale.Category
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getDisplayName
public final String getDisplayName(Locale locale)
Returns a long standard time name of thisTimeZonesuitable for presentation to the user in the specifiedlocale.This method is equivalent to:
getDisplayName(false,
LONG, locale)- Parameters:
locale- the locale in which to supply the display name.- Returns:
- the human-readable name of this time zone in the given locale.
- Throws:
NullPointerException- iflocaleisnull.- Since:
- 1.2
- See Also:
getDisplayName(boolean, int, Locale)
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getDisplayName
public final String getDisplayName(boolean daylight, int style)
Returns a name in the specifiedstyleof thisTimeZonesuitable for presentation to the user in the default locale. If the specifieddaylightistrue, a Daylight Saving Time name is returned (even if thisTimeZonedoesn't observe Daylight Saving Time). Otherwise, a Standard Time name is returned.This method is equivalent to:
getDisplayName(daylight, style, Locale.getDefault(Locale.Category.DISPLAY))- Parameters:
daylight-truespecifying a Daylight Saving Time name, orfalsespecifying a Standard Time namestyle- eitherLONGorSHORT- Returns:
- the human-readable name of this time zone in the default locale.
- Throws:
IllegalArgumentException- ifstyleis invalid.- Since:
- 1.2
- See Also:
getDisplayName(boolean, int, Locale),Locale.getDefault(Locale.Category),Locale.Category,DateFormatSymbols.getZoneStrings()
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getDisplayName
public String getDisplayName(boolean daylight, int style, Locale locale)
Returns a name in the specifiedstyleof thisTimeZonesuitable for presentation to the user in the specifiedlocale. If the specifieddaylightistrue, a Daylight Saving Time name is returned (even if thisTimeZonedoesn't observe Daylight Saving Time). Otherwise, a Standard Time name is returned.When looking up a time zone name, the default
Localesearch path ofResourceBundlederived from the specifiedlocaleis used. (No fallbackLocalesearch is performed.) If a time zone name in anyLocaleof the search path, includingLocale.ROOT, is found, the name is returned. Otherwise, a string in the normalized custom ID format is returned.- Parameters:
daylight-truespecifying a Daylight Saving Time name, orfalsespecifying a Standard Time namestyle- eitherLONGorSHORTlocale- the locale in which to supply the display name.- Returns:
- the human-readable name of this time zone in the given locale.
- Throws:
IllegalArgumentException- ifstyleis invalid.NullPointerException- iflocaleisnull.- Since:
- 1.2
- See Also:
DateFormatSymbols.getZoneStrings()
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getDSTSavings
public int getDSTSavings()
Returns the amount of time to be added to local standard time to get local wall clock time.The default implementation returns 3600000 milliseconds (i.e., one hour) if a call to
useDaylightTime()returnstrue. Otherwise, 0 (zero) is returned.If an underlying
TimeZoneimplementation 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.If the amount of saving time at any given time stamp is required, construct a
Calendarwith thisTimeZoneand the time stamp, and callCalendar.get(Calendar.DST_OFFSET).- Returns:
- the amount of saving time in milliseconds
- Since:
- 1.4
- See Also:
inDaylightTime(Date),getOffset(long),getOffset(int,int,int,int,int,int),Calendar.ZONE_OFFSET
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useDaylightTime
public abstract boolean useDaylightTime()
Queries if thisTimeZoneuses Daylight Saving Time.If an underlying
TimeZoneimplementation 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 callingobservesDaylightTime()if the current rule should also be taken into account.- Returns:
trueif thisTimeZoneuses Daylight Saving Time,false, otherwise.- See Also:
inDaylightTime(Date),Calendar.DST_OFFSET
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observesDaylightTime
public boolean observesDaylightTime()
Returnstrueif thisTimeZoneis currently in Daylight Saving Time, or if a transition from Standard Time to Daylight Saving Time occurs at any future time.The default implementation returns
trueifuseDaylightTime()orinDaylightTime(new Date())returnstrue.- Returns:
trueif thisTimeZoneis currently in Daylight Saving Time, or if a transition from Standard Time to Daylight Saving Time occurs at any future time;falseotherwise.- Since:
- 1.7
- See Also:
useDaylightTime(),inDaylightTime(Date),Calendar.DST_OFFSET
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inDaylightTime
public abstract boolean inDaylightTime(Date date)
Queries if the givendateis in Daylight Saving Time in this time zone.- Parameters:
date- the given Date.- Returns:
trueif the given date is in Daylight Saving Time,false, otherwise.
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getTimeZone
public static TimeZone getTimeZone(String ID)
Gets theTimeZonefor the given ID.- Parameters:
ID- the ID for aTimeZone, 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.- Returns:
- the specified
TimeZone, or the GMT zone if the given ID cannot be understood.
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getTimeZone
public static TimeZone getTimeZone(ZoneId zoneId)
Gets theTimeZonefor the givenzoneId.- Parameters:
zoneId- aZoneIdfrom which the time zone ID is obtained- Returns:
- the specified
TimeZone, or the GMT zone if the given ID cannot be understood. - Throws:
NullPointerException- ifzoneIdisnull- Since:
- 1.8
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toZoneId
public ZoneId toZoneId()
Converts thisTimeZoneobject to aZoneId.- Returns:
- a
ZoneIdrepresenting the same time zone as thisTimeZone - Since:
- 1.8
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getAvailableIDs
public static String[] getAvailableIDs(int rawOffset)
Gets the available IDs according to the given time zone offset in milliseconds.- Parameters:
rawOffset- the given time zone GMT offset in milliseconds.- Returns:
- 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 Also:
getRawOffset()
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getAvailableIDs
public static String[] getAvailableIDs()
Gets all the available IDs supported.- Returns:
- an array of IDs.
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getDefault
public static TimeZone getDefault()
Gets the defaultTimeZoneof the Java virtual machine. If the cached defaultTimeZoneis available, its clone is returned. Otherwise, the method takes the following steps to determine the default time zone.- Use the
user.timezoneproperty value as the default time zone ID if it's available. - Detect the platform time zone ID. The source of the platform time zone and ID mapping may vary with implementation.
- Use
GMTas the last resort if the given or detected time zone ID is unknown.
The default
TimeZonecreated from the ID is cached, and its clone is returned. Theuser.timezoneproperty value is set to the ID upon return.- Returns:
- the default
TimeZone - See Also:
setDefault(TimeZone)
- Use the
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setDefault
public static void setDefault(TimeZone zone)
Sets theTimeZonethat is returned by thegetDefaultmethod.zoneis cached. Ifzoneis null, the cached defaultTimeZoneis cleared. This method doesn't change the value of theuser.timezoneproperty.- Parameters:
zone- the new defaultTimeZone, or null- Throws:
SecurityException- if the security manager'scheckPermissiondeniesPropertyPermission("user.timezone", "write")- See Also:
getDefault(),PropertyPermission
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hasSameRules
public boolean hasSameRules(TimeZone other)
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.- Parameters:
other- theTimeZoneobject to be compared with- Returns:
- 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
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