TimeZone, DateFormat & Daylight Savings time - help please

Question

Our system holds dates on the database as GMT. I need to display these dates in local times, taking into account time zone differences and daylight savings time. An example:
DateFormat format = new SimpleDateFormat("HH:mm");
format.setTimeZone(TimeZone.getTimeZone("Europe/London"));
GregorianCalendar calendar = new GregorianCalendar(2003,6,31,13,20,25);
System.out.println(format.format(calendar.getTime()));
format.setTimeZone(TimeZone.getTimeZone("Europe/Istanbul"));
System.out.println(format.format(calendar.getTime()));
This code produces the following output
13:20
15:20
What hasn't been taken into account is that both time zones are in daylight savings time so both dates should be one hour on. TimeZone has all the methods to establish and adjust the date so I'm surprised that the formatter doesn't use these. If I use them manually to adjust the date then everything works OK but I didn't think I'd have to do that. Anyone help me in getting the right results? Is this a bug or do I need to do something different? I'm using JDK 1.4.1
Many thanks
Ian

Answer 1

I still can't get this working how I want. The date that I will be trying to parse will be a GMT date, not a BST date.
SimpleDateFormat format = new SimpleDateFormat("yyyy-MMM-dd HH:mm:ss");
TimeZone timeZone = TimeZone.getTimeZone("Europe/London");
Date date = null;
try {
date = format.parse("2003-Jul-31 13:20:25");
} catch (ParseException ex) {
System.out.println(format.format(date));
format.setTimeZone(TimeZone.getTimeZone("Europe/Istanbul"));
System.out.println(format.format(date));
format.setTimeZone(TimeZone.getTimeZone("Africa/Freetown"));
System.out.println(format.format(date));
This is the output
2003-Jul-31 13:20:25
2003-Jul-31 15:20:25
2003-Jul-31 12:20:25
My desired output is
2003-Jul-31 14:20:25 GMT +1 hour DST
2003-Jul-31 16:20:25 GMT +1 hour DST +2 hours time zone difference
2003-Jul-31 13:20:25 GMT
Any ideas?
Cheers
Ian