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 Calendar
@see GregorianCalendar
@see SimpleTimeZone
@version 1.76 12/07/07
@author Mark Davis, David Goldsmith, Chen-Lieh Huang, Alan Liu
@since JDK1.1