java.sql.Timestamp#valueOf result depends on default timezone

Question

I've made experiment

for (String tz: TimeZone.getAvailableIDs()) {
    TimeZone.setDefault(TimeZone.getTimeZone(tz));
    timestamp = Timestamp.valueOf("1970-01-01 00:00:00.000");
    System.out.println(tz + " - " + timestamp.getTime());
}

unexpectedly result was different for each timezone. What is the logic behind this? always thought that timestamp is timezone-independant.

`"1970-01-01 00:00:00.000"` had to be interpreted in the context of _some_ timezone, so it uses the default timezone. Did you think it would just use UTC? — GriffeyDog, Oct 20 '16 at 15:12
@GriffeyDog yep, the problem is that date string comes from DB and it is treated as UTC date — x__dos, Oct 20 '16 at 15:14
`String`s don't have a timezone. To convert from a `String` to a `Timestamp`, a timezone needs to be applied. `valueOf` uses the default timezone to make the conversion from `String` to `Timestamp`. — GriffeyDog, Oct 20 '16 at 15:16
@GriffeyDog hmm strange that Timestamp doesn't support specifying timezone in string then — x__dos, Oct 20 '16 at 15:56
See dup link, and also [this answer](http://stackoverflow.com/a/14070771/634824) for a more detailed explanation. — Matt Johnson-Pint, Oct 20 '16 at 20:19

Raider · Answer 1 · 2016-10-21T06:27:40.607

0

Because Timestamp use UTC TimeZone, if you change Timezone It will be different, i.e. when in London was 1970-01-01 00:00:00.000 (GMT+1) in spanish Canary Islands was 1969-12-31 23:00:00.000 (GMT)

*EDIT: For most purposes, UTC is considered interchangeable with GMT

edited Oct 21 '16 at 06:27

answered Oct 20 '16 at 15:18

Raider

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Actually, at 1970-01-01, London was at GMT+1, and Canary Islands were at GMT. Your times are correct, but your offsets are both off by an hour. – Matt Johnson-Pint Oct 20 '16 at 20:15
@MattJohnson Thanks for aclaration! – Raider Oct 21 '16 at 06:28

java.sql.Timestamp#valueOf result depends on default timezone

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