set JVM timezone in Linux

[shital sonavane]

Hi all,
I want to change my JVM's timezone from IST to SGT. My Operating System is Centos. Please guide me for this....
Thanks in advance.

[James Sabre]

Why do you think you need to do this? This does not really make sense so there is normally no need to do this. The class java.util.Date store the date as the number of milliseconds since 1/1/1970 00:00:00 UTC regardless of the platform timezone. The JVM uses the platform default timezone for converting java.util.Date to String or String to java.utll.Date but you should specify a timezone for these conversions when using SimpleDataFormat or java.utl.Calendar. This way your application will be correct regardless of the default platform timezone.

[shital sonavane]

I am saving date by converting it into long and while doing this i am getting problem. because when date is converted to long it is considers the timezone.
Therefor i want to change my systems timezone for data conversion according to SGT timezone.

[James Sabre]

shital sonavane wrote:I am saving date by converting it into long and while doing this i am getting problem. because when date is converted to long it is considers the timezone.
Therefor i want to change my systems timezone for data conversion according to SGT timezone.

Sorry but I don't really understand. java.util.Date.getTime() provides the number of milliseconds since 1/1/1970 00:00:00 UTC. What use case requires a different epoch and/or time zone? If you have a valid use case then I still don't see the need to change the JVM time zone. What stops you creating methods to generate the milliseconds in the time zone you desire and convert back from this value to java.util.Date.

[Paul Clapham]

If you want to parse or format dates using SimpleDateFormat, and you want to use a specific timezone to do that, then the simplest thing to do is to create the SimpleDateFormat object and then call its setTimeZone(TimeZone) method to set that specific timezone. You don't need to change the whole JVM.

You'll have to find the real name of the time zone, though, "SGT" isn't going to do.

[Jesper de Jong]

Shital, can you show us the code that you are currently using to convert the date to a long?

As James and Paul have already mentioned, changing the timezone setting of your system is most likely not the right solution for the problem that you are having.

[shital sonavane]

hey guys thanks. i found the solution.
I did this using

TimeZone.setDefault(TimeZone.getTimeZone("GMT+8")); 

.

[shital sonavane]

This is the code i am using to convert date into long.

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            Date date = (Date) sdf.parse(frmDate);
            long longDate = date.getTime();

[Jesper de Jong]

Instead of setting the default timezone, you should set the timezone on the SimpleDateFormat object:

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
sdf.setTimeZone(TimeZone.getTimeZone("GMT+8"));

Date date = (Date) sdf.parse(frmDate);
long longDate = date.getTime();