MainThreadTest.java

/*
 * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
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 */

/*
 * @test
 * @bug     4533087
 * @summary Test to see if the main thread is in its thread group
 */

public class MainThreadTest {
    public static void main(String args[]) {
        ThreadGroup tg = Thread.currentThread().getThreadGroup();
        int n = tg.activeCount();
        Thread[] ts = new Thread[n];
        int m = tg.enumerate(ts);
        for (int i = 0; i < ts.length; i++) {
            if (Thread.currentThread() == ts[i]) {
                return;
            }
        }
        throw new RuntimeException(
            "Current thread is not in its own thread group!");
    }
}