alt Hacker NewsA ZonedDateTime is not an instant and a timezone, for the same reason that you can’t unambiguously round trip between arbitrary timezones and UTC:
- zoned datetimes carry ambiguities as to their actual location on the timeline (because they can repeat, or not exist at all)
- future zoned datetime carry outright uncertainty as to their actual location on the timeline (as the zone’s offset can be updated at any point and any number of times until the event has elapsed)
Replies
paulddraper • today at 1:01 PM
A java.time.ZonedDateTime is not simply zoneid+date+time.
It has the zone offset and so is completely unambiguous and invariable.
private final LocalDateTime dateTime;
private final ZoneOffset offset;
private final ZoneId zone;
ulrikrasmussen • today at 10:48 AM
Ah, yes, you are right! Forgot about those two details
Has anyone proposed versioning timezones? Or is this such an edge case it would be overkill? (Either specify your future instant in UTC if you mean to stick to that, or specify it in a timezone and accept that it could change before it happens, or if you need something else get it in a contract and don't trust the computer!)