Java ThreadGroup setDaemon()方法

java.lang.ThreadGroup.setDaemon() 方法改变该线程组的守护进程的状态。当其最后一个线程被停止或它的最后一个线程组被销毁守护线程组会自动销毁。

1 语法

public final void setDaemon(boolean daemon)

2 参数

daemon ： 如果为true，这标志着该线程组作为守护线程组;否则，标志着该线程组为正常。

3 返回值

此方法不返回任何值。

4 示例

package com.yiidian;

/**

* 一点教程网： http://www.yiidian.com

*/

/**

* Java ThreadGroup setDaemon()方法

*/

import java.lang.*;

public class ThreadGroupDemo implements Runnable

{

public static void main(String[] args) {

ThreadGroupDemo tg = new ThreadGroupDemo();

tg.func();

}

public void func() {

try {

// create a parent ThreadGroup

ThreadGroup pGroup = new ThreadGroup("Parent ThreadGroup");

// daemon status is set to true

pGroup.setDaemon(true);

// create a child ThreadGroup for parent ThreadGroup

ThreadGroup cGroup = new ThreadGroup(pGroup, "Child ThreadGroup");

// daemon status is set to true

cGroup.setDaemon(true);

// create a thread

Thread t1 = new Thread(pGroup, this);

System.out.println("Starting " + t1.getName() + "...");

t1.start();

// create another thread

Thread t2 = new Thread(cGroup, this);

System.out.println("Starting " + t2.getName() + "...");

t2.start();

// returns true if this thread group is a daemon thread group

System.out.println("Is " + pGroup.getName() + " a daemon

ThreadGroup? " + pGroup.isDaemon());

System.out.println("Is " + cGroup.getName() + " a daemon

ThreadGroup? " + cGroup.isDaemon());

// block until the other threads finish

t1.join();

t2.join();

}

catch (InterruptedException ex) {

System.out.println(ex.toString());

}

}

// implements run()

public void run() {

for(int i = 0;i < 1000;i++) {

i++;

}

System.out.println(Thread.currentThread().getName() +

" finished executing.");

}

}

输出结果为：

Starting Thread-0...

Starting Thread-1...

Is Parent ThreadGroup a daemonThreadGroup? true

Is Child ThreadGroup a daemonThreadGroup? true

Thread-0 finished executing.

Thread-1 finished executing.