Conversion of local time zone to GMT in java

Am trying convert date which is in local time zone to GMT, i did some thing like this

SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");
        sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
        String gmtStrDate = sdf.format(Calendar.getInstance().getTime());

        System.out.println("GMT 1"+gmtStrDate);

        Date gmtDate = sdf.parse(gmtStrDate);

        System.out.println("GMT 2"+gmtDate);

i am getting GMT 1 o/p in GMT 开发者_Python百科tz but GMT 2 o/p is again changing to local time zone...Can any tel me why?

to get the GMT 2 o/p in GMT i did like this :

Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("GMT")); calendar.setTime(gmtDate);

        System.out.println("GMT 3 = "+calendar.getTime());

but still GMT 3o/p am getting in local tz. Please suggest on this.

import java.util.*;
import java.text.*;
public class CurrentTimeToGMT{
  public static void main(String args[]){
    Date date = new Date();
    DateFormat gmtFormat = new SimpleDateFormat();
    TimeZone gmtTime = TimeZone.getTimeZone("GMT");
    gmtFormat.setTimeZone(gmtTime);
    System.out.println("Current Time: "+date);
    System.out.println("GMT Time: " + gmtFormat.format(date));

  }
}

Output

Current Time: Wed Mar 10 11:21:18 IST 2010

GMT Time: 3/10/10 5:51 AM

After 'parse' you have to again format it before printing, e.g.:

System.out.println("GMT 2"+sdf.format(gmtDate));

EDIT: The reason is your gmtStrDate doesn't store any timezone information

You can do this using this function say you want to convert local time to GMT time and also this will be GMT+6 or GMT+5 then just use this function. This function will return answer.

public String getCurrentDate() {
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy MM dd hh:mm a zzz");
    Date date = new Date();
    sdf.setTimeZone(TimeZone.getTimeZone("GMT+6:00"));
    return sdf.format(date);
 }