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Java Date Time

1 Java Date and Time Tutorial
2 Java System.currentTimeMillis()
3 Java Time Measurement
4 Java's java.util.Date
5 Java's java.sql.Date
6 Java's java.sql.Timestamp
7 Java's java.util.Calendar and GregorianCalendar
8 Java's java.util.TimeZone
9 Parsing and Formatting Dates in Java




Java's java.util.TimeZone


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.

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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