守护线程

没有守护

public class TestDemo {
    public static void main(String[] args) throws InterruptedException {
        Thread thread = new Thread(() -> {
            while (true) {
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("[守护线程]");
            }
        });
//        thread.setDaemon(true); // true表示为守护线程
        thread.start();
        Thread.sleep(1000);
        System.out.println("主线程退出");
    }
}

[守护线程]
[守护线程]
[守护线程]
[守护线程]
[守护线程]
[守护线程]
[守护线程]
[守护线程]
[守护线程]
主线程退出
[守护线程]
[守护线程]

主线程结束 , 非守护线程不结束

守护线程

public class TestDemo {
    public static void main(String[] args) throws InterruptedException {
        Thread thread = new Thread(() -> {
            while (true) {
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("[守护线程]");
            }
        });
        thread.setDaemon(true);
        thread.start();
        Thread.sleep(1000);
        System.out.println("主线程退出");
    }
}

[守护线程]
[守护线程]
[守护线程]
[守护线程]
[守护线程]
[守护线程]
[守护线程]
[守护线程]
[守护线程]
主线程退出

主线程结束 , 守护线程结束