Java's java.util.TimeZone
Jakob Jenkov |
The Java TimeZone class is a class that represents time zones, and is helpful when doing calendar arithmetics across time zones.
The java.util.TimeZone class is used in conjunction with the
java.util.Calendar class.
Note: In the Java 8 date time API the time zones are represented by the java.time.ZoneId class.
But you only need to use the ZoneId class if you are using the Java 8 date time classes (like
the ZonedDateTime class). If you use a Calendar
(from the Java 7 and earlier date time API) you can still use the java.util.TimeZone class.
Obtaining a TimeZone from a Calendar
Here is a simple example of how you can get the TimeZone from a Calendar:
Calendar calendar = new GregorianCalendar(); TimeZone timeZone = calendar.getTimeZone();
And here is how you can set it:
calendar.setTimeZone(timeZone);
Creating a TimeZone Instance
There are two ways to obtain a TimeZone instance:
TimeZone timeZone = TimeZone.getDefault();
TimeZone timeZone = TimeZone.getTimeZone("Europe/Copenhagen");
The first method (TimeZone.getDefault()) returns the default time zone for
the system (computer) this program is running on.
The second method (TimeZone.getTimeZone("Europe/Copenhagen")) returns the
TimeZone corresponding to the given time zone ID (in this example
"Europe/Copenhagen"). There is a list of available time zone ID's at the end of this
text.
Time Zone Names, ID's and Offsets
You can see the display name, ID and time offset of a given time zone like this:
timeZone.getDisplayName(); timeZone.getID(); timeZone.getOffset( System.currentTimeMillis() );
The getOffset() method returns the offset in milliseconds for the given
time zone to UTC, at the given time. For instance, the "Europe/Copenhagen" time zone
may have one hour offset during the winter, and two hours during the summer time due
to daylight savings.
Converting Between Time Zones
You can covert the date and time in a Calendar between different
time zones. Here is an example of how to do this:
TimeZone timeZone1 = TimeZone.getTimeZone("America/Los_Angeles");
TimeZone timeZone2 = TimeZone.getTimeZone("Europe/Copenhagen");
Calendar calendar = new GregorianCalendar();
long timeCPH = calendar.getTimeInMillis();
System.out.println("timeCPH = " + timeCPH);
System.out.println("hour = " + calendar.get(Calendar.HOUR_OF_DAY));
calendar.setTimeZone(timeZone1);
long timeLA = calendar.getTimeInMillis();
System.out.println("timeLA = " + timeLA);
System.out.println("hour = " + calendar.get(Calendar.HOUR_OF_DAY));
This example prints out this:
timeHere = 1264881305341 hour = 20 timeLA = 1264881305341 hour = 11
Notice how the time in milliseconds is the same with both time zones, but that the
hour of day has changed from 20 to 11. There is a 9 hour time difference
between Copenhagen and LA. Copenhagen is 9 hours ahead of LA. The Calendar
class is capable of converting the date and time between time zones.
Available Time Zones
Here is a list of the available time zone ids in the TimeZone class, printed
as returned by TimeZone.getAvailableIDs().
Etc/GMT+12 Etc/GMT+11 MIT Pacific/Apia Pacific/Midway Pacific/Niue Pacific/Pago_Pago Pacific/Samoa US/Samoa America/Adak America/Atka Etc/GMT+10 HST Pacific/Fakaofo Pacific/Honolulu Pacific/Johnston Pacific/Rarotonga Pacific/Tahiti SystemV/HST10 US/Aleutian US/Hawaii Pacific/Marquesas AST America/Anchorage America/Juneau America/Nome America/Yakutat Etc/GMT+9 Pacific/Gambier SystemV/YST9 SystemV/YST9YDT US/Alaska America/Dawson America/Ensenada America/Los_Angeles America/Tijuana America/Vancouver America/Whitehorse Canada/Pacific Canada/Yukon Etc/GMT+8 Mexico/BajaNorte PST PST8PDT Pacific/Pitcairn SystemV/PST8 SystemV/PST8PDT US/Pacific US/Pacific-New America/Boise America/Cambridge_Bay America/Chihuahua America/Dawson_Creek America/Denver America/Edmonton America/Hermosillo America/Inuvik America/Mazatlan America/Phoenix America/Shiprock America/Yellowknife Canada/Mountain Etc/GMT+7 MST MST7MDT Mexico/BajaSur Navajo PNT SystemV/MST7 SystemV/MST7MDT US/Arizona US/Mountain America/Belize America/Cancun America/Chicago America/Costa_Rica America/El_Salvador America/Guatemala America/Managua America/Menominee America/Merida America/Mexico_City America/Monterrey America/North_Dakota/Center America/Rainy_River America/Rankin_Inlet America/Regina America/Swift_Current America/Tegucigalpa America/Winnipeg CST CST6CDT Canada/Central Canada/East-Saskatchewan Canada/Saskatchewan Chile/EasterIsland Etc/GMT+6 Mexico/General Pacific/Easter Pacific/Galapagos SystemV/CST6 SystemV/CST6CDT US/Central America/Bogota America/Cayman America/Detroit America/Eirunepe America/Fort_Wayne America/Grand_Turk America/Guayaquil America/Havana America/Indiana/Indianapolis America/Indiana/Knox America/Indiana/Marengo America/Indiana/Vevay America/Indianapolis America/Iqaluit America/Jamaica America/Kentucky/Louisville America/Kentucky/Monticello America/Knox_IN America/Lima America/Louisville America/Montreal America/Nassau America/New_York America/Nipigon America/Panama America/Pangnirtung America/Port-au-Prince America/Porto_Acre America/Rio_Branco America/Thunder_Bay America/Toronto Brazil/Acre Canada/Eastern Cuba EST EST5EDT Etc/GMT+5 IET Jamaica SystemV/EST5 SystemV/EST5EDT US/East-Indiana US/Eastern US/Indiana-Starke US/Michigan America/Anguilla America/Antigua America/Aruba America/Asuncion America/Barbados America/Boa_Vista America/Campo_Grande America/Caracas America/Cuiaba America/Curacao America/Dominica America/Glace_Bay America/Goose_Bay America/Grenada America/Guadeloupe America/Guyana America/Halifax America/La_Paz America/Manaus America/Martinique America/Montserrat America/Port_of_Spain America/Porto_Velho America/Puerto_Rico America/Santiago America/Santo_Domingo America/St_Kitts America/St_Lucia America/St_Thomas America/St_Vincent America/Thule America/Tortola America/Virgin Antarctica/Palmer Atlantic/Bermuda Atlantic/Stanley Brazil/West Canada/Atlantic Chile/Continental Etc/GMT+4 PRT SystemV/AST4 SystemV/AST4ADT America/St_Johns CNT Canada/Newfoundland AGT America/Araguaina America/Bahia America/Belem America/Buenos_Aires America/Catamarca America/Cayenne America/Cordoba America/Fortaleza America/Godthab America/Jujuy America/Maceio America/Mendoza America/Miquelon America/Montevideo America/Paramaribo America/Recife America/Rosario America/Sao_Paulo Antarctica/Rothera BET Brazil/East Etc/GMT+3 America/Noronha Atlantic/South_Georgia Brazil/DeNoronha Etc/GMT+2 America/Scoresbysund Atlantic/Azores Atlantic/Cape_Verde Etc/GMT+1 Africa/Abidjan Africa/Accra Africa/Bamako Africa/Banjul Africa/Bissau Africa/Casablanca Africa/Conakry Africa/Dakar Africa/El_Aaiun Africa/Freetown Africa/Lome Africa/Monrovia Africa/Nouakchott Africa/Ouagadougou Africa/Sao_Tome Africa/Timbuktu America/Danmarkshavn Atlantic/Canary Atlantic/Faeroe Atlantic/Madeira Atlantic/Reykjavik Atlantic/St_Helena Eire Etc/GMT Etc/GMT+0 Etc/GMT-0 Etc/GMT0 Etc/Greenwich Etc/UCT Etc/UTC Etc/Universal Etc/Zulu Europe/Belfast Europe/Dublin Europe/Lisbon Europe/London GB GB-Eire GMT GMT0 Greenwich Iceland Portugal UCT UTC Universal WET Zulu Africa/Algiers Africa/Bangui Africa/Brazzaville Africa/Ceuta Africa/Douala Africa/Kinshasa Africa/Lagos Africa/Libreville Africa/Luanda Africa/Malabo Africa/Ndjamena Africa/Niamey Africa/Porto-Novo Africa/Tunis Africa/Windhoek Arctic/Longyearbyen Atlantic/Jan_Mayen CET ECT Etc/GMT-1 Europe/Amsterdam Europe/Andorra Europe/Belgrade Europe/Berlin Europe/Bratislava Europe/Brussels Europe/Budapest Europe/Copenhagen Europe/Gibraltar Europe/Ljubljana Europe/Luxembourg Europe/Madrid Europe/Malta Europe/Monaco Europe/Oslo Europe/Paris Europe/Prague Europe/Rome Europe/San_Marino Europe/Sarajevo Europe/Skopje Europe/Stockholm Europe/Tirane Europe/Vaduz Europe/Vatican Europe/Vienna Europe/Warsaw Europe/Zagreb Europe/Zurich MET Poland ART Africa/Blantyre Africa/Bujumbura Africa/Cairo Africa/Gaborone Africa/Harare Africa/Johannesburg Africa/Kigali Africa/Lubumbashi Africa/Lusaka Africa/Maputo Africa/Maseru Africa/Mbabane Africa/Tripoli Asia/Amman Asia/Beirut Asia/Damascus Asia/Gaza Asia/Istanbul Asia/Jerusalem Asia/Nicosia Asia/Tel_Aviv CAT EET Egypt Etc/GMT-2 Europe/Athens Europe/Bucharest Europe/Chisinau Europe/Helsinki Europe/Istanbul Europe/Kaliningrad Europe/Kiev Europe/Minsk Europe/Nicosia Europe/Riga Europe/Simferopol Europe/Sofia Europe/Tallinn Europe/Tiraspol Europe/Uzhgorod Europe/Vilnius Europe/Zaporozhye Israel Libya Turkey Africa/Addis_Ababa Africa/Asmera Africa/Dar_es_Salaam Africa/Djibouti Africa/Kampala Africa/Khartoum Africa/Mogadishu Africa/Nairobi Antarctica/Syowa Asia/Aden Asia/Baghdad Asia/Bahrain Asia/Kuwait Asia/Qatar Asia/Riyadh EAT Etc/GMT-3 Europe/Moscow Indian/Antananarivo Indian/Comoro Indian/Mayotte W-SU Asia/Riyadh87 Asia/Riyadh88 Asia/Riyadh89 Mideast/Riyadh87 Mideast/Riyadh88 Mideast/Riyadh89 Asia/Tehran Iran Asia/Aqtau Asia/Baku Asia/Dubai Asia/Muscat Asia/Oral Asia/Tbilisi Asia/Yerevan Etc/GMT-4 Europe/Samara Indian/Mahe Indian/Mauritius Indian/Reunion NET Asia/Kabul Asia/Aqtobe Asia/Ashgabat Asia/Ashkhabad Asia/Bishkek Asia/Dushanbe Asia/Karachi Asia/Samarkand Asia/Tashkent Asia/Yekaterinburg Etc/GMT-5 Indian/Kerguelen Indian/Maldives PLT Asia/Calcutta IST Asia/Katmandu Antarctica/Mawson Antarctica/Vostok Asia/Almaty Asia/Colombo Asia/Dacca Asia/Dhaka Asia/Novosibirsk Asia/Omsk Asia/Qyzylorda Asia/Thimbu Asia/Thimphu BST Etc/GMT-6 Indian/Chagos Asia/Rangoon Indian/Cocos Antarctica/Davis Asia/Bangkok Asia/Hovd Asia/Jakarta Asia/Krasnoyarsk Asia/Phnom_Penh Asia/Pontianak Asia/Saigon Asia/Vientiane Etc/GMT-7 Indian/Christmas VST Antarctica/Casey Asia/Brunei Asia/Chongqing Asia/Chungking Asia/Harbin Asia/Hong_Kong Asia/Irkutsk Asia/Kashgar Asia/Kuala_Lumpur Asia/Kuching Asia/Macao Asia/Macau Asia/Makassar Asia/Manila Asia/Shanghai Asia/Singapore Asia/Taipei Asia/Ujung_Pandang Asia/Ulaanbaatar Asia/Ulan_Bator Asia/Urumqi Australia/Perth Australia/West CTT Etc/GMT-8 Hongkong PRC Singapore Asia/Choibalsan Asia/Dili Asia/Jayapura Asia/Pyongyang Asia/Seoul Asia/Tokyo Asia/Yakutsk Etc/GMT-9 JST Japan Pacific/Palau ROK ACT Australia/Adelaide Australia/Broken_Hill Australia/Darwin Australia/North Australia/South Australia/Yancowinna AET Antarctica/DumontDUrville Asia/Sakhalin Asia/Vladivostok Australia/ACT Australia/Brisbane Australia/Canberra Australia/Hobart Australia/Lindeman Australia/Melbourne Australia/NSW Australia/Queensland Australia/Sydney Australia/Tasmania Australia/Victoria Etc/GMT-10 Pacific/Guam Pacific/Port_Moresby Pacific/Saipan Pacific/Truk Pacific/Yap Australia/LHI Australia/Lord_Howe Asia/Magadan Etc/GMT-11 Pacific/Efate Pacific/Guadalcanal Pacific/Kosrae Pacific/Noumea Pacific/Ponape SST Pacific/Norfolk Antarctica/McMurdo Antarctica/South_Pole Asia/Anadyr Asia/Kamchatka Etc/GMT-12 Kwajalein NST NZ Pacific/Auckland Pacific/Fiji Pacific/Funafuti Pacific/Kwajalein Pacific/Majuro Pacific/Nauru Pacific/Tarawa Pacific/Wake Pacific/Wallis NZ-CHAT Pacific/Chatham Etc/GMT-13 Pacific/Enderbury Pacific/Tongatapu Etc/GMT-14 Pacific/Kiritimati
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Jakob Jenkov | |
