Conversion of local time zone to GMT in java

Question

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 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.

Answer 1

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

Answer 2

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

Answer 3

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);
 }