TimeZone insanity

[rejefi]

Hello, I'm attempting to find the difference between two dates, which (may) be in different timezones. One set of timezones will always be GMT; the others will vary. I simulate the problem in the following code:

TimeZone t1 = TimeZone.getTimeZone("PDT");
TimeZone t2 = TimeZone.getTimeZone("GMT");
Calendar c1 = Calendar.getInstance(t1);
Calendar c2 = Calendar.getInstance(t2);
long diff = c1.getTimeInMillis() - c2.getTimeInMillis();

diff is always 0, counterintuitively (at least to me).

What do I need to do to make this work?

Thanks

 

[rejefi]

OK, google to the rescue. Here's the code. Ugggly.

TimeZone t1 = TimeZone.getTimeZone("PST");
TimeZone t2 = TimeZone.getTimeZone("GMT");
Calendar c1 = Calendar.getInstance(t1);
Calendar c2 = Calendar.getInstance(t2);
long diff = (c1.getTimeInMillis() + c1.getTimeZone().getOffset(c1.getTimeInMillis())) - (c2.getTimeInMillis() + c2.getTimeZone().getOffset(c2.getTimeInMillis()));   
long hoursDiff = diff / (60 * 60 * 1000);