线程分用户线程和守护线程

虚拟机必须确保用户线程执行完毕

虚拟机不用等待守护线程执行完毕

后台记录操作日志，监控内存，垃圾回收

package com.wuming.state;
//测试守护线程
//上帝守护你
public class TestDaemon {public static void main(String[] args) {God god = new God();You you = new You();Thread thread = new Thread(god);thread.setDaemon(true);//默认是false表示用户线程，正常的线程都是用户线程。。。thread.start();//上帝守护线程启动new Thread(you).start();//你，用户线程启动}
}
//上帝
class God implements Runnable{/*** When an object implementing interface <code>Runnable</code> is used* to create a thread, starting the thread causes the object's* <code>run</code> method to be called in that separately executing* thread.* <p>* The general contract of the method <code>run</code> is that it may* take any action whatsoever.** @see Thread#run()*/@Overridepublic void run() {while(true){System.out.println("上帝保佑着你");}}
}
//你
class You implements Runnable{/*** When an object implementing interface <code>Runnable</code> is used* to create a thread, starting the thread causes the object's* <code>run</code> method to be called in that separately executing* thread.* <p>* The general contract of the method <code>run</code> is that it may* take any action whatsoever.** @see Thread#run()*/@Overridepublic void run() {for (int i = 0; i < 36500; i++) {System.out.println("你一生都开心的活着");}System.out.println("goodbye====world!!");}
}