Java,wait,notify,notifyAll的使用方法_JobShow裁员加班实况-微信小程序

import java.util.Date;

public class NotifyTest {
    private String[] flag = new String[]{"true"};

    class NotifyThread extends Thread {
        public NotifyThread(String name) {
            super(name);
            System.out.println("NotifyThread 构造函数 "+new Date());
        }
        public void run() {
            System.out.println("NotifyThread 进入run "+new Date());
            try {
                System.out.println("NotifyThread 开始sleep "+new Date());
                sleep(3000);//推迟3秒钟通知
                System.out.println("NotifyThread 结束sleep "+new Date());
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

//            flag = "false";
//            flag.notify();//Exception in thread "notify01" java.lang.IllegalMonitorStateException，没有拿到flag对象的控制权，添加 synchronized (flag)

//            synchronized (flag){
//                flag = "false";//对在同步块中对flag进行了赋值操作，使得flag引用的对象改变，这时候再调用notify方法时，因为没有控制权所以抛出异常。
//                flag.notify();//Exception in thread "notify01" java.lang.IllegalMonitorStateException
//            }

//             synchronized (flag){
//                 flag[0] = "false";
//                 flag.notify();  //只输出了一个，wait time :3001  waiter01 end waiting!
//             }

            synchronized (flag){
                System.out.println("NotifyThread  进入synchronized  已获得flag的控制权");
                flag[0] = "false";//这里的修改对程序运行不起作用
                flag.notifyAll(); //三个线程都会输出
                try {
                    sleep(3000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("NotifyThread  退出synchronized 已释放flag的控制权");
            }
            System.out.println("NotifyThread 退出run "+new Date());
        }//run
    };

    class WaitThread extends Thread {
        public WaitThread(String name) {
            super(name);
        }
        public void run() {
            synchronized (flag) { //后来添加
                while (flag[0].equals("true")) {//Exception in thread "waiter01" java.lang.IllegalMonitorStateException，没有拿到flag对象的控制权，添加 synchronized (flag) {}
                    System.out.println(getName() + " begin waiting!");
                    long waitTime = System.currentTimeMillis();
                    try {
                        flag.wait();//在这里等待，暂停执行。获得控制权后才能继续执行
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    waitTime = System.currentTimeMillis() - waitTime;
                    System.out.println("wait time :" + waitTime);
                }
                System.out.println(getName() + " end waiting!");
            }
        }//run
    }

    public static void main(String[] args) throws InterruptedException {
        System.out.println("Main Thread Begin!");
        NotifyTest test = new NotifyTest();
        NotifyThread notifyThread = test.new NotifyThread("notify01");
        WaitThread waitThread01 = test.new WaitThread("waiter01");
        WaitThread waitThread02 = test.new WaitThread("waiter02");
        WaitThread waitThread03 = test.new WaitThread("waiter03");
        notifyThread.start();
        waitThread01.start();
        waitThread02.start();
        waitThread03.start();
        System.out.println("Main Thread End!");
    }
}

/*Main Thread Begin!
NotifyThread 构造函数 Tue Dec 05 15:44:52 CST 2017
Main Thread End!
waiter02 begin waiting!
NotifyThread 进入run Tue Dec 05 15:44:52 CST 2017
NotifyThread 开始sleep Tue Dec 05 15:44:52 CST 2017
waiter03 begin waiting!
waiter01 begin waiting!
NotifyThread 结束sleep Tue Dec 05 15:44:55 CST 2017
NotifyThread  进入synchronized  已获得flag的控制权
NotifyThread  退出synchronized 已释放flag的控制权
NotifyThread 退出run Tue Dec 05 15:44:58 CST 2017
wait time :5978
waiter01 end waiting!
wait time :5981
waiter03 end waiting!
wait time :6001
waiter02 end waiting!*/


import java.util.Date;

public class NotifyT