Here you can find the source of memoryUsed()
public static long memoryUsed()
//package com.java2s; /*/*w w w. ja v a2s. c o m*/ * Copyright (C) 2010-2101 Alibaba Group Holding Limited. * * 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 { public static long memoryUsed() { Runtime rt = Runtime.getRuntime(); return rt.totalMemory() - rt.freeMemory(); } }