DateFormat Z has wrong offset ?

Question

Been adding TimeZone i18n to an application and have found that the GMT offset for some of the timezones found within the JVM doesnt match their names. This is best explained with an example
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Locale;
import java.util.TimeZone;
public class TimeZoneTest {
    public static void main(String[] args) throws Exception {
        SimpleDateFormat formatter = new SimpleDateFormat("Z", Locale.getDefault());
        TimeZone tz = TimeZone.getTimeZone("Etc/GMT+8");
        formatter.setTimeZone(tz);
        String offset = formatter.format(Calendar.getInstance().getTime());
        System.out.println("TimeZone ID: " + tz.getID());
        System.out.println("TimeZone GMT Offset(Z): " + offset);
}when i run this code i get the following result:
TimeZone ID: Etc/GMT+8
TimeZone GMT Offset(Z): -0800
Based on the timezone id i would expect the offset(Z) to be +0800.
Can someone please explain this to me.
Thanks
Sam

Answer 1

That is because "Etc/GMT+8" came from the UNIX world which handles GMT offsets the other way around. If you need GMT+8, you could use "GMT+8" which is called a `custom' time zone ID. It's normalized to "GMT+08:00" in getTimeZone().
Masayoshi