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Convert ZonedDateTime to LocalDateTime at time zone

I have an object of ZonedDateTime that is constructed like this

ZonedDateTime z = ZonedDateTime.of(LocalDate.now().atTime(11, 30), ZoneOffset.UTC);

How can I convert it to LocalDateTime at time zone of Switzerland? Expected result should be 16 april 2018 13:30.

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Vitalii Avatar asked Apr 16 '18 09:04

Vitalii


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How do I convert ZonedDateTime to another timezone?

Changing Timezones of ZonedDateTime To convert a ZonedDateTime instance from one timezone to another, follow the two steps: Create ZonedDateTime in 1st timezone. You may already have it in your application. Convert the first ZonedDateTime in second timezone using withZoneSameInstant() method.

How do I get LocalDateTime from ZonedDateTime?

The LocalDateTime has no time zone; to convert the LocalDateTime to ZonedDateTime , we can use . atZone(ZoneId. systemDefault()) to create a ZonedDateTime containing the system default time zone and convert it to another time zone using a predefined zone id or offset.

How do I get LocalDateTime from my timezone?

In your case: // your local date/time with no timezone information LocalDateTime localNow = LocalDateTime. now(); // setting UTC as the timezone ZonedDateTime zonedUTC = localNow. atZone(ZoneId.

Is ZonedDateTime a UTC?

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4 Answers

How can I convert it to LocalDateTime at time zone of Switzerland?

You can convert the UTC ZonedDateTime into a ZonedDateTime with the time zone of Switzerland, but maintaining the same instant in time, and then get the LocalDateTime out of that, if you need to. I'd be tempted to keep it as a ZonedDateTime unless you need it as a LocalDateTime for some other reason though.

ZonedDateTime utcZoned = ZonedDateTime.of(LocalDate.now().atTime(11, 30), ZoneOffset.UTC);
ZoneId swissZone = ZoneId.of("Europe/Zurich");
ZonedDateTime swissZoned = utcZoned.withZoneSameInstant(swissZone);
LocalDateTime swissLocal = swissZoned.toLocalDateTime();
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Jon Skeet Avatar answered Oct 29 '22 16:10

Jon Skeet


It helps to understand the difference between LocalDateTime and ZonedDateTime. What you really want is a ZonedDateTime. If you wanted to remove the timezone from the string representation, you would convert it to a LocalDateTime.

What you're looking for is: ZonedDateTime swissZonedDateTime = withZoneSameInstant(ZoneId.of("Europe/Zurich"));

LocalDateTime - this is basically a glorified string representation of a Date and Time; it is timezone agnostic, which means it does not represent any point in time on a timeline

Instant - this is a millisecond representation of time that has elapsed since EPOCH. This represents a specific instant in time on a timeline

ZonedDateTime - this also represents an instant in time on a timeline, but it represents it as a Date and Time with a TimeZone.

The code below illustrates how to use all 3.

LocalDateTime localDateTime = LocalDateTime.of(2018, 10, 25, 12, 00, 00);  //October 25th at 12:00pm
ZonedDateTime zonedDateTimeInUTC = localDateTime.atZone(ZoneId.of("UTC")); 
ZonedDateTime zonedDateTimeInEST = zonedDateTimeInUTC.withZoneSameInstant(ZoneId.of("America/New_York")); 
    
System.out.println(localDateTime.toString()); // 018-10-25T12:00
System.out.println(zonedDateTimeInUTC.toString()); // 2018-10-25T12:00Z[UTC]
System.out.println(zonedDateTimeInEST.toString()); // 2018-10-25T08:00-04:00[America/New_York]

If you were to compare the Instant values of both ZonedDateTimes from above, they would be equivalent because they both point to the same instant in time. Somewhere in Greenwich (UTC timezone), it is noon on October 25th; at the same time, in New York, it would be 8 am (America/NewYork timezone).

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Stevers Avatar answered Oct 29 '22 15:10

Stevers


Try this out. Substitute US/Central with your timezone.

ZonedDateTime z = ZonedDateTime.of(LocalDate.now().atTime(11, 30), ZoneOffset.UTC);

System.out.println(z.withZoneSameInstant(ZoneId.of("US/Central")));
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Ravindra Ranwala Avatar answered Oct 29 '22 17:10

Ravindra Ranwala


Another option that seems a little more intuitive is to convert the zoned date to an instant, then use LocalDateTime.ofInstant:

ZonedDateTime zdt = ZonedDateTime.of(LocalDate.now().atTime(11, 30), ZoneOffset.UTC);
ZoneId zId = ZoneId.of("US/Central");
LocalDateTime l = LocalDateTime.ofInstant(zdt.toInstant(), zId);

I prefer this to withZoneSameInstant because that solution little more opaque - you're getting a ZonedDateTime that has to be in a particular internal state (the correct time zone). Using ofInstant can be used on any ZonedDateTime in any time zone.

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Jon Nichols Avatar answered Oct 29 '22 16:10

Jon Nichols