CODEWITHSUNDEEP
javadatetimetimezoneutc
daydreamer
daydreamer

Reputation: 91959

How to get Timezone from DateTime, Latitude and Longitude (No External API)?

There is an excellent answer on how to get TimeZone given a Latitude and Longitude. There is however a comment in the answer as

One thing I've noticed is the lack of any UTC timestamp requirement when determining the time zone. For instance, a long/lat in London is not enough to determine weather the time zone is GMT or BST (British Summer Time / daylight savings). So surely to determine the correct time zone you need lat, long and a UTC timestamp.

Also, there is a wiki, which talks that Java has it's own database for Timezones, which is documented on Oracle website

I am wondering that given a UTC Datetime, Latitude and Longitude, is there a way to leverage the Java's timezone database to get the timezone instead of making API calls?

Any resources/examples?

Upvotes: 2

Views: 6903

Answers (1)

Matt Johnson-Pint
Matt Johnson-Pint

Reputation: 241475

The article you referenced shows several libraries that work offline, including one for Java. These libraries look up lat/lon against the tz_world map, then give you back a standard IANA time zone identifier, such as America/New_York.

Then, you use that identifier with whatever timestamp to convert, using Java libraries or standard Java. The best approach is to use Joda-Time for Java 7 and earlier, and use the new java.time package for Java 8+.

There's not a one-step implementation, because these are two different concerns. You might need both in some cases, but not always.

Upvotes: 2

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