Android : How to convert current date time from IST to EST timezone in Android?

How to get the EST timzone date (already convrted and get String) into date format with its Timezone? I tried with changing timezone and I got the perfect datetime in string format but while I am parsing that String date into date format it gives me local Android system timezone time.

Thanks for any help...in advance.

DateFormat outputFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm aa");
TimeZone tz = TimeZone.getTimeZone("EST");
outputFormat.setTimeZone(tz);
String current_date =  outputFormat.format(date);
Date currentdate = outputFormat.parse(current_date);

It give's me EST date format in String (current_date). It give's me IST format date (currentdate)