Java TimeZones: how to get UTC time values based on Console settings?

Question

For example, when I extract from a database a Date() variable, it contains a date with "+04:00" shift. According to my locale's settings. So, UTC time is "ourTime" MINUS 4 hours.

Then, a user tells where he/she is from. Now, we need to save his/her shift. LET'S SAY it is -01:00. And finally, this user tells us where's he/she is heading, let's say this place has a time shift of +05:00.

How do we save this town's or place's time shifts in the DB so that according to where he/she's from we could calculate the time difference with our current locale? Also, date save light things, how do we work with them?

Answer 1

You don't.

As long as you're using java.util.Date objects (or java.sql.Date, or java.sql.Timestamp) the database will contain UTC time, that's what java.util.Date holds internally.

You need to format and/or parse these dates according to local timezone. Take a look at SimpleDateFormat for more information. Of course, if you have dates in the database that you manually parsed, then you may be SOL.