Get current time in a given timezone : android

Question

I am new to Android and I am currently facing an issue to get current time given the timezone.

I get timezone in the format \"GMT-7\" i.e. string. and I have the sys

Answer 1

java.time

Both the older date-time classes bundled with Java and the third-party Joda-Time library have been supplanted by the java.time framework built into Java 8 and later. These classes supplant the old troublesome date-time classes such as java.util.Date. See Oracle Tutorial. Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport and further adapted to Android in ThreeTenABP.

By the way, never refer to an offset-from-UTC with a single digit of hours such as -7, as that is non-standard and will be incompatible with various protocols and libraries. Always pad with a zero for second digit, such as -07.

If all you have is an offset rather than a time zone, use the OffsetDateTime class.

ZoneOffset offset = ZoneOffset.ofHours( -7 );
OffsetDateTime odt = OffsetDateTime.now( offset );
String output1 = odt.toLocalTime().toString();
System.out.println( "Current time in " + offset + ": " + output1 );

Current time in -07:00: 19:41:36.525

If you have a full time zone, which is an offset plus a set of rules for handling anomalies such as Daylight Saving Time (DST), rather than a mere offset-from-UTC, use the ZonedDateTime class.

ZoneId denverTimeZone = ZoneId.of( "America/Denver" );
ZonedDateTime zdt = ZonedDateTime.now( denverTimeZone );
String output2 = zdt.toLocalTime().toString();
System.out.println( "Current time in " + denverTimeZone + ": " + output2 );

Current time in America/Denver: 20:41:36.560

See this code in action in Ideone.com.

Joda-Time

You can use Joda-Time 2.7 in Android. Makes date-time work much easier.

DateTimeZone zone = DateTimeZone.forID ( "America/Denver" );
DateTime dateTime = new DateTime ( zone );
String output = dateTime.toLocalTime ().toString ();

dump to console.

System.out.println ( "zone: " + zone + " | dateTime: " + dateTime + " | output: " + output );

When run…

zone: America/Denver | dateTime: 2016-07-11T20:50:17.668-06:00 | output: 20:50:17.668

Count Since Epoch

I strongly recommend against tracking by time by count-since-epoch. But if necessary, you can extract Joda-Time’s internal milliseconds-since-epoch (Unix time, first moment of 1970 UTC) by calling the getMillis method on a DateTime.

Note the use of the 64-bit long rather than 32-bit int primitive types.

In java.time. Keep in mind that you may be losing data here, as java.time holds a resolution up to nanoseconds. Going from nanoseconds to milliseconds means truncating up to six digits of a decimal fraction of a second (3 digits for milliseconds, 9 for nanoseconds).

long millis = Instant.now ().toEpochMilli ();

In Joda-Time.

long millis = DateTime.now( denverTimeZone ).getMillis();