Datetime parsing and formatting

Datetime parsing is a switch from a string datetime to a complex datetime, and datetime formatting is a switch from a complex datetime to a string datetime.

A DateTimeFormatter is a complex type (object) that defines the allowed sequence of characters for a string datetime. Datetime parsing and formatting often require a DateTimeFormatter. For more information about how to use a DateTimeFormatter see the Java documentation.

• Parse from milliseconds:

  String milliSinceEpochString = "434931330000";
  long milliSinceEpoch = Long.parseLong(milliSinceEpochString);
  Instant instant = Instant.ofEpochMilli(milliSinceEpoch);
  ZonedDateTime zdt = ZonedDateTime.ofInstant(instant, ZoneId.of('Z'));
  

• Parse from ISO 8601:

  String datetime = '1983-10-13T22:15:30Z';
  ZonedDateTime zdt = ZonedDateTime.parse(datetime);
  

  1. The parse method uses ISO 8601 by default.

• Parse from RFC 1123:

  String datetime = 'Thu, 13 Oct 1983 22:15:30 GMT';
  ZonedDateTime zdt = ZonedDateTime.parse(datetime,
          DateTimeFormatter.RFC_1123_DATE_TIME);
  

  1. This uses a built-in DateTimeFormatter.

• Parse from a custom format:

  String datetime = 'custom y 1983 m 10 d 13 22:15:30 Z';
  DateTimeFormatter dtf = DateTimeFormatter.ofPattern(
          "'custom' 'y' yyyy 'm' MM 'd' dd HH:mm:ss VV");
  ZonedDateTime zdt = ZonedDateTime.parse(datetime, dtf);
  

  1. This uses a custom DateTimeFormatter.

• Format to ISO 8601:

  ZonedDateTime zdt =
          ZonedDateTime.of(1983, 10, 13, 22, 15, 30, 0, ZoneId.of('Z'));
  String datetime = zdt.format(DateTimeFormatter.ISO_INSTANT);
  

  1. This uses a built-in DateTimeFormatter.

• Format to a custom format:

  ZonedDateTime zdt =
          ZonedDateTime.of(1983, 10, 13, 22, 15, 30, 0, ZoneId.of('Z'));
  DateTimeFormatter dtf = DateTimeFormatter.ofPattern(
          "'date:' yyyy/MM/dd 'time:' HH:mm:ss");
  String datetime = zdt.format(dtf);
  

  1. This uses a custom DateTimeFormatter.