How to covernt a date/time to another time zone?

Question

The current system (Unix) is what I'm running programs on.
When I get the current date and time it is in GMT time.
I tried to create a new Calendar and specify TimeZone.getTimeZone("EST") then use the getTime() function to get my Date, but that still displaed it in GMT time.

Answer 1

java.util.Date and java.util.Calendar have no real concept of Timezone, they only know about GMT. They store the number of ms since January 1, 1970 00:00:00.000 GMT. When you display a value you use a Timezone to work out how the time should be calculated.
For example -
import java.util.Date;
import java.text.SimpleDateFormat;
import java.util.TimeZone;
public class Test20041116
    public static void main(String[] args)
        Date now = new Date();
        SimpleDateFormat local = new SimpleDateFormat("dd/MM/yyyy hh:mm:ss z");
        System.out.println("Local time (Here) = " + local.format(now));
        local.setTimeZone(TimeZone.getTimeZone("EST"));
        System.out.println("Local time (EST)  = " + local.format(now));
        local.setTimeZone(TimeZone.getTimeZone("PST"));
        System.out.println("Local time (PST)  = " + local.format(now));
}