Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/*
 * ThreadUtils.java
 *
 * Created on Feb 26, 2010, 12:10:25 PM
 *
 * Description: Provides thread utility methods.
 *
 * Copyright (C) Feb 26, 2010 reed.
 *
 * 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, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

import java.lang.management.ManagementFactory;
import java.lang.management.ThreadMXBean;
import java.util.ArrayList;
import java.util.List;

public class Main {
    /** the root JVM thread group */
    private static ThreadGroup rootThreadGroup = null;

    /** Returns a list of all threads.
     *
     * @return a list of all threads
     */
    public static List<Thread> getAllThreads() {
        final ThreadGroup root = getRootThreadGroup();
        final ThreadMXBean thbean = ManagementFactory.getThreadMXBean();
        int nAlloc = thbean.getThreadCount();
        @SuppressWarnings("UnusedAssignment")
        int n = 0;
        Thread[] threads;
        do {
            nAlloc *= 2;
            threads = new Thread[nAlloc];
            n = root.enumerate(threads, true);
        } while (n == nAlloc);
        final List<Thread> threadList = new ArrayList<>();
        for (final Thread thread : threads) {
            if (thread != null) {
                threadList.add(thread);
            }
        }
        return threadList;
    }

    /** Returns the root thread group.
     *
     * @return the root thread group
     */
    public synchronized static ThreadGroup getRootThreadGroup() {
        if (rootThreadGroup == null) {
            rootThreadGroup = Thread.currentThread().getThreadGroup();
            ThreadGroup parentThreadGroup;
            while ((parentThreadGroup = rootThreadGroup.getParent()) != null) {
                rootThreadGroup = parentThreadGroup;
            }
        }
        return rootThreadGroup;
    }
}