Here you can find the source of diffInMillis(long instantOne, long instantTwo)
public static long diffInMillis(long instantOne, long instantTwo)
//package com.java2s; /**//from w ww .j a v a2s. c om * Confidential Information. * Copyright (C) 2003, 2004, 2005, 2006 Eric Link, All rights reserved. * PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. **/ public class Main { /** * Diff is for instant, does not consider time zone **/ public static long diffInMillis(long instantOne, long instantTwo) { return instantTwo - instantOne; } }