JAVA中的多线程(七)：停止线程和守护线程，join方法

stop方法已经过时

如何停止线程？

只有一种，run方法结束

开始多线程运行，运行代码通常是循环结构

只要控制住循环，就可以让run方法结束，也就是线程结束

 

特殊情况

当线程处于冻结状态

就不会读取到标记，那么线程就不会结束

当没有指定的方式让冻结的线程恢复到运行状态时，这时就需要对冻结状态进行清除

强制让线程恢复到运行状态中来，这样就可以操作标记让线程结束

Thread类中提供了该方法interrupt();

class StopThread implements Runnable
{
    private boolean flag = true;
    public synchronized void run()
    {
        while(flag)
        {
            try
            {
                wait();
            }
            catch(InterruptedException e)
            {
                System.out.println(Thread.currentThread().getName()+"...InterruptedException");
                flag = false;
            }
            System.out.println(Thread.currentThread().getName()+"...run");
        }
    }
    public void changeFlag()
    {
        flag = false;
    }
}
class StopThreadDemo
{
    public static void main(String[] args)
    {
        StopThread st = new StopThread();
        Thread t1 = new Thread(st);
        Thread t2 = new Thread(st);
        
        t1.start();
        t2.start();
        
        int num = 0;
        while(true)
        {
            if(num++ == 60)
            {
                //st.changeFlag();
                t1.interrupt();
                break;
            }
            System.out. println(Thread.currentThread().getName()+"...num");
        }
        System.out.println("over");
    }
}

 守护线程需要在线程启动前设置

当运行的线程都是守护线程的时候，JAVA虚拟机退出

class StopThread implements Runnable
{
    private boolean flag = true;
    public synchronized void run()
    {
        while(flag)
        {
            try
            {
                wait();
            }
            catch(InterruptedException e)
            {
                System.out.println(Thread.currentThread().getName()+"...InterruptedException");
                flag = false;
            }
            System.out.println(Thread.currentThread().getName()+"...run");
        }
    }
    public void changeFlag()
    {
        flag = false;
    }
}
class StopThreadDemo
{
    public static void main(String[] args)
    {
        StopThread st = new StopThread();
        Thread t1 = new Thread(st);
        Thread t2 = new Thread(st);
        
        t1.setDaemon(true);
        t1.setDaemon(true);
        t1.start();
        t2.start();
        
        int num = 0;
        while(true)
        {
            if(num++ == 60)
            {
                //st.changeFlag();
                t1.interrupt();
                break;
            }
            System.out. println(Thread.currentThread().getName()+"...num");
        }
        System.out.println("over");
    }
}

 当A线程执行到了B线程的.join()方法时，A就会等待，等B线程执都行完，A才会执行

join可以用来临时加入线程执行

class Demo implements Runnable
{
    public void run()
    {
        for(int x = 0; x < 70; x++)
        {
            System.out.println(Thread.currentThread().getName()+"..."+x);
        }
    }
}

class JoinDemo
{
    public static void main(String[] args) throws Exception
    {
        Demo d = new Demo();
        Thread t1 = new Thread(d);
        Thread t2 = new Thread(d);
        t1.start();
        t1.join();
        t2.start();
        for(int x = 0; x < 70; x++)
        {
            System.out.println("main..."+x);
        }
        System.out.println("over");
    }
}