Here you can find the source of currentTimeMillis()
public static long currentTimeMillis()
//package com.java2s; /**/* w ww . j ava 2 s .co m*/ * Copyright 2011 Google Inc. * Copyright 2014 Andreas Schildbach * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ public class Main { /** * If non-null, overrides the return value of now(). */ public static volatile Date mockTime; /** Returns the current time in seconds since the epoch, or a mocked out equivalent. */ public static long currentTimeMillis() { if (mockTime != null) return mockTime.getTime(); else return System.currentTimeMillis(); } }