Datetime Modification

Use either a numeric datetime or a complex datetime to do modifications such as adding several seconds to a datetime or subtracting several days from a datetime. Use standard numeric operators to modify a numeric datetime. Use methods (or fields) to modify a complex datetime. Many complex datetimes are immutable, so upon modification a new complex datetime is created that requires assignment or immediate use.

• Subtract three seconds from a numeric datetime in milliseconds:

  long milliSinceEpoch = 434931330000L;
  milliSinceEpoch = milliSinceEpoch - 1000L*3L;
  

• Add three days to a complex datetime:

  ZonedDateTime zdt =
          ZonedDateTime.of(1983, 10, 13, 22, 15, 30, 0, ZoneId.of('Z'));
  ZonedDateTime updatedZdt = zdt.plusDays(3);
  

• Subtract 125 minutes from a complex datetime:

  ZonedDateTime zdt =
          ZonedDateTime.of(1983, 10, 13, 22, 15, 30, 0, ZoneId.of('Z'));
  ZonedDateTime updatedZdt = zdt.minusMinutes(125);
  

• Set the year on a complex datetime:

  ZonedDateTime zdt =
          ZonedDateTime.of(1983, 10, 13, 22, 15, 30, 0, ZoneId.of('Z'));
  ZonedDateTime updatedZdt = zdt.withYear(1976);