Here you can find the source of millisToGMT(long millis)
public static String millisToGMT(long millis)
//package com.java2s; import java.text.SimpleDateFormat; import java.util.Locale; import java.util.TimeZone; public class Main { /**// www. ja v a2s . c om * */ public static String millisToGMT(long millis) { SimpleDateFormat df = new SimpleDateFormat("MM_dd_yyyy_hh_mm", Locale.getDefault()); df.setTimeZone(TimeZone.getTimeZone("GMT")); return df.format(millis) + "_UTC"; } }