Datetime zone

Both string datetimes and complex datetimes have a timezone with a default of UTC. Numeric datetimes do not have enough explicit information to have a timezone, so UTC is always assumed. Use methods (or fields) in conjunction with a ZoneId to change the timezone for a complex datetime. Parse a string datetime into a complex datetime to change the timezone, and then format the complex datetime back into a desired string datetime. Many complex datetimes are immutable, so upon modification a new complex datetime is created that requires assignment or immediate use.

• Modify the timezone for a complex datetime:

  ZonedDateTime utc =
          ZonedDateTime.of(1983, 10, 13, 22, 15, 30, 0, ZoneId.of('Z'));
  ZonedDateTime pst = utc.withZoneSameInstant(ZoneId.of('America/Los_Angeles'));
  

• Modify the timezone for a string datetime:

  String gmtString = 'Thu, 13 Oct 1983 22:15:30 GMT';
  ZonedDateTime gmtZdt = ZonedDateTime.parse(gmtString,
          DateTimeFormatter.RFC_1123_DATE_TIME);
  ZonedDateTime pstZdt =
          gmtZdt.withZoneSameInstant(ZoneId.of('America/Los_Angeles'));
  String pstString = pstZdt.format(DateTimeFormatter.RFC_1123_DATE_TIME);
  

  1. This uses a built-in DateTimeFormatter.