Here you can find the source of getMemoryFree()
public static long getMemoryFree()
//package com.java2s; /*//from ww w. j a v a 2 s .c o m Storybook: Scene-based software for novelists and authors. Copyright (C) 2008 - 2012 Martin Mustun This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ public class Main { public static long getMemoryFree() { return Runtime.getRuntime().freeMemory(); } }