什么是守护线程
守护线程是为用户线程服务的这么一个线程，主线程结束，守护线程也结束
package com.cppdy;
class MyThread3 extends Thread{
@Override
public void run() {
System.out.println("开始执行线程");
try {
sleep(1000);
} catch (Exception e) {
}
System.out.println("结束执行线程");
}
}
public class ThreadDemo3 {
public static void main(String[] args) throws Exception{
MyThread3 mt = new MyThread3();
//设置守护线程
mt.setDaemon(true);
mt.start();
Thread.sleep(500);
}
}