Timezone issue in Android

I have time in milliseconds and I am displaying that time in my application in "MM/dd/yyyy HH:mm:ss" format, it is working fine.

Problem: if I change the timezone in android device it display different time in my application may be because of some timezone calculation. I want to display same time that is in my database as it is in any timezone.

I am using below code to test timezone issue

Locale locale = new Locale("en", "IN");

TimeZone tz = TimeZone.getDefault();
System.out.println("Default timezon id :: " + tz.getID());
tz.setID("Asia/Calcutta");
String timezon = tz.getDisplayName(false, TimeZone.SHORT, locale);
System.out.println("Timezon id :: " + tz.getID() + " Timezon name :: " + timezon);
Calendar cal = Calendar.getInstance(tz, locale);

System.out.println("TImezon :: " + tz);
// "1319084400775" is the milliseconds of 10/20/2011 05:20:00 in MM/dd/yyyy HH:mm:ss format 
Date date = new Date(Long.parseLong("1319084400775"));
System.out.println("Date :: " + date.toGMTString());
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss", locale);

System.out.println("Start date :: " + format.format(date));
// "1319084400775" is the milliseconds of 10/20/2011 05:20:00 in MM/dd/yyyy HH:mm:ss format 
cal.setTimeInMillis(Long.parseLong("1319084400775"));

timezon = cal.getTimeZone().getDisplayName(false, TimeZone.SHORT, locale);
System.out.println("Calender's timezon :: " + timezon);
System.out.println("Start date :: yyyy-mm-dd hh:mm:ss " + cal.get(Calendar.YEAR) + "-" + cal.get(Calendar.MONTH) + "-" + cal.get(Calendar.DAY_OF_MONTH) + " " + cal.get(Calendar.HOUR_OF_DAY) + ":" + cal.get(Calendar.MINUTE));
// "1319084700776" is the milliseconds of 10/20/2011 05:25:00 in MM/dd/yyyy HH:mm:ss format 
cal.setTimeInMillis(Long.parseLong("1319084700776"));
System.out.println("End date :: " + cal.getTime());

Output ::

If I set timezon