守护(daemon)线程

◆线程分为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
◆如，后台记录操作日志，监控内存，垃圾回收等待. . .

package state;
// 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表示是用户线程，正常的线程都是用户线程

        thread.start();//守护线程启动

        new Thread(you).start();//用户线程启动
    }
}

class God implements Runnable{
    @Override
    public void run() {
        while (true){
            System.out.println("God bless you!");
        }
    }
}

class You implements Runnable{
    @Override
    public void run() {
        for (int i = 0; i < 36500; i++) {
            System.out.println("You live happily all your life.");
        }
        System.out.println("========Goodbye!World!=========");
    }
}