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Added in API level 1

TimeZone

public abstract class TimeZone
extends Object implements Serializable, Cloneable

java.lang.Object
   ↳ java.util.TimeZone
Known Direct Subclasses


TimeZone represents a time zone offset, and also figures out daylight savings.

Typically, you get a TimeZone using getDefault which creates a TimeZone based on the time zone where the program is running. For example, for a program running in Japan, getDefault creates a TimeZone object based on Japanese Standard Time.

You can also get a TimeZone using getTimeZone 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 TimeZone object with:

 TimeZone tz = TimeZone.getTimeZone("America/Los_Angeles");
 
You can use the getAvailableIDs method to iterate through all the supported time zone IDs. You can then choose a supported ID to get a TimeZone. 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:
 CustomID:
         GMT Sign Hours : Minutes
         GMT Sign Hours Minutes
         GMT Sign Hours
 Sign: one of
         + -
 Hours:
         Digit
         Digit Digit
 Minutes:
         Digit Digit
 Digit: one of
         0 1 2 3 4 5 6 7 8 9
 
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.

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, "GMT" is used.

When creating a TimeZone, the specified custom time zone ID is normalized in the following syntax:

 NormalizedCustomID:
         GMT Sign TwoDigitHours : Minutes
 Sign: one of
         + -
 TwoDigitHours:
         Digit Digit
 Minutes:
         Digit Digit
 Digit: one of
         0 1 2 3 4 5 6 7 8 9
 
For example, TimeZone.getTimeZone("GMT-8").getID() returns "GMT-08:00".

Three-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.

See also:

Summary

Constants

int LONG

A style specifier for getDisplayName() indicating a long name, such as "Pacific Standard Time."

int SHORT

A style specifier for getDisplayName() indicating a short name, such as "PST."

Public constructors

TimeZone()

Sole constructor.

Public methods

Object clone()

Creates a copy of this TimeZone.

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.

int getDSTSavings()

Returns the amount of time to be added to local standard time to get local wall clock time.

static TimeZone getDefault()

Gets the default TimeZone for this host.

String getDisplayName(boolean daylightTime, int style, Locale locale)

Returns the short or long name of this time zone with either standard or daylight time, as written in locale.

final String getDisplayName(Locale locale)

Returns a long standard time name of this TimeZone suitable for presentation to the user in the specified locale.

final String getDisplayName(boolean daylight, int style)

Returns a name in the specified style of this TimeZone suitable for presentation to the user in the default locale.

final String getDisplayName()

Returns a long standard time name of this TimeZone suitable for presentation to the user in the default locale.

String getID()

Gets the ID of this time zone.

int getOffset(long date)

Returns the offset of this time zone from UTC at the specified date.

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.

abstract int getRawOffset()

Returns the amount of time in milliseconds to add to UTC to get standard time in this time zone.

static TimeZone getTimeZone(String id)

Gets the TimeZone for the given ID.

boolean hasSameRules(TimeZone other)

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

abstract boolean inDaylightTime(Date date)

Queries if the given date is in Daylight Saving Time in this time zone.

boolean observesDaylightTime()

Returns true if this TimeZone is currently in Daylight Saving Time, or if a transition from Standard Time to Daylight Saving Time occurs at any future time.

static void setDefault(TimeZone timeZone)

Sets the TimeZone that is returned by the getDefault method.

void setID(String ID)

Sets the time zone ID.

abstract void setRawOffset(int offsetMillis)

Sets the base time zone offset to GMT.

abstract boolean useDaylightTime()

Queries if this TimeZone uses Daylight Saving Time.

Inherited methods

From class java.lang.Object

Constants

LONG

Added in API level 1
int LONG

A style specifier for getDisplayName() indicating a long name, such as "Pacific Standard Time."

See also:

Constant Value: 1 (0x00000001)

SHORT

Added in API level 1
int SHORT

A style specifier for getDisplayName() indicating a short name, such as "PST."

See also:

Constant Value: 0 (0x00000000)

Public constructors

TimeZone

Added in API level 1
TimeZone ()

Sole constructor. (For invocation by subclass constructors, typically implicit.)

Public methods

clone

Added in API level 1
Object clone ()

Creates a copy of this TimeZone.

Returns
Object a clone of this TimeZone

getAvailableIDs

Added in API level 1
String[] getAvailableIDs ()

Gets all the available IDs supported.

Returns
String[] an array of IDs.

getAvailableIDs

Added in API level 1
String[] getAvailableIDs (int rawOffset)

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

Parameters
rawOffset int: the given time zone GMT offset in milliseconds.
Returns
String[] 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:

getDSTSavings

Added in API level 1
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() returns true. Otherwise, 0 (zero) is returned.

If an underlying 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.

If the amount of saving time at any given time stamp is required, construct a Calendar with this TimeZone and the time stamp, and call Calendar.get(DST_OFFSET).

Returns
int the amount of saving time in milliseconds

See also:

getDefault

Added in API level 1
TimeZone getDefault ()

Gets the default TimeZone for this host. The source of the default TimeZone may vary with implementation.

Returns
TimeZone a default TimeZone.

See also:

getDisplayName

Added in API level 1
String getDisplayName (boolean daylightTime, 
                int style, 
                Locale locale)

Returns the short or long name of this time zone with either standard or daylight time, as written in locale. If the name is not available, the result is in the format GMT[+-]hh:mm.

Parameters
daylightTime boolean: true for daylight time, false for standard time.
style int: either LONG or SHORT.
locale Locale: the display locale.
Returns
String

getDisplayName

Added in API level 1
String getDisplayName (Locale locale)

Returns a long standard time name of this TimeZone suitable for presentation to the user in the specified locale.

This method is equivalent to:

getDisplayName(false, LONG, locale)

Parameters
locale Locale: the locale in which to supply the display name.
Returns
String the human-readable name of this time zone in the given locale.
Throws
NullPointerException if locale is null.

See also:

getDisplayName

Added in API level 1
String getDisplayName (boolean daylight, 
                int style)

Returns a name in the specified style of this TimeZone suitable for presentation to the user in the default locale. If the specified daylight is true, a Daylight Saving Time name is returned (even if this TimeZone doesn't observe Daylight Saving Time). Otherwise, a Standard Time name is returned.

This method is equivalent to:

getDisplayName(daylight, style, Locale.getDefault(DISPLAY))

Parameters
daylight boolean: true specifying a Daylight Saving Time name, or false specifying a Standard Time name
style int: either LONG or SHORT
Returns
String the human-readable name of this time zone in the default locale.
Throws
IllegalArgumentException if style is invalid.

See also:

getDisplayName

Added in API level 1
String getDisplayName ()

Returns a long standard time name of this TimeZone suitable for presentation to the user in the default locale.

This method is equivalent to:

getDisplayName(false, LONG, Locale.getDefault(DISPLAY))

Returns
String the human-readable name of this time zone in the default locale.

See also:

getID

Added in API level 1
String getID ()

Gets the ID of this time zone.

Returns
String the ID of this time zone.

getOffset

Added in API level 1
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 long: the date represented in milliseconds since January 1, 1970 00:00:00 GMT
Returns
int the amount of time in milliseconds to add to UTC to get local time.

See also:

getOffset

Added in API level 1
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 TimeZone implementation subclass supports historical Daylight Saving Time schedule and GMT offset changes.

Parameters
era int: the era of the given date.
year int: the year in the given date.
month int: the month in the given date. Month is 0-based. e.g., 0 for January.
day int: the day-in-month of the given date.
dayOfWeek int: the day-of-week of the given date.
milliseconds int: the milliseconds in day in standard local time.
Returns
int the offset in milliseconds to add to GMT to get local time.

See also:

getRawOffset

Added in API level 1
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 TimeZone 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).

Returns
int the amount of raw offset time in milliseconds to add to UTC.

See also:

getTimeZone

Added in API level 1
TimeZone getTimeZone (String id)

Gets the TimeZone for the given ID.

Parameters
id String: the ID for a TimeZone, 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
TimeZone the specified TimeZone, or the GMT zone if the given ID cannot be understood.

hasSameRules

Added in API level 1
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 TimeZone: the TimeZone object to be compared with
Returns
boolean true if the other zone is not null and is the same as this one, with the possible exception of the ID

inDaylightTime

Added in API level 1
boolean inDaylightTime (Date date)

Queries if the given date is in Daylight Saving Time in this time zone.

Parameters
date Date: the given Date.
Returns
boolean true if the given date is in Daylight Saving Time, false, otherwise.

observesDaylightTime

Added in API level 24
boolean observesDaylightTime ()

Returns true if this TimeZone is 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 true if useDaylightTime() or inDaylightTime(new Date()) returns true.

Returns
boolean true if this TimeZone is currently in Daylight Saving Time, or if a transition from Standard Time to Daylight Saving Time occurs at any future time; false otherwise.

See also:

setDefault

Added in API level 1
void setDefault (TimeZone timeZone)

Sets the TimeZone that is returned by the getDefault method. If zone is null, reset the default to the value it had originally when the VM first started.

Parameters
timeZone TimeZone: the new default time zone

See also:

setID

Added in API level 1
void setID (String ID)

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

Parameters
ID String: the new time zone ID.

setRawOffset

Added in API level 1
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 TimeZone 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.

Parameters
offsetMillis int: the given base time zone offset to GMT.

useDaylightTime

Added in API level 1
boolean useDaylightTime ()

Queries if this TimeZone uses Daylight Saving Time.

If an underlying 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 observesDaylightTime() if the current rule should also be taken into account.

Returns
boolean true if this TimeZone uses Daylight Saving Time, false, otherwise.

See also:

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