三个线程之间的通信

//使用while循环，当线程1执行结束后唤醒其他所有线程并释放锁，线程1和线程2和线程3争抢锁，需要确保线程2争取到锁，假设线程3和线程1抢到锁则进入waiting状态。依次类推。。。。。
public class Demo {
    static int flag = 1;
    static Object ob = new Object();

    public static void main(String[] args) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                while (true) {
                    synchronized (ob) {
                        while (flag != 1) {
                            try {
                                ob.wait();
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                        method1();
                        flag = 2;
                        ob.notifyAll();
                    }
                }
            }
        }).start();

        new Thread() {
            @Override
            public void run() {
                while (true) {
                    synchronized (ob) {
                        while (flag != 2) {
                                try {
                                    ob.wait();
                                } catch (InterruptedException e) {
                                    e.printStackTrace();
                                }
                        }
                        method2();
                        flag = 3;
                        ob.notifyAll();
                    }
                }
            }
        }.start();

        new Thread() {
            @Override
            public void run() {
                while (true) {
                    synchronized (ob) {
                        while (flag != 3) {
                            try {
                                ob.wait();
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                        method3();
                        flag = 1;
                        ob.notifyAll();
                    }
                }
            }
        }.start();


    }
    
    public static void method1(){
        System.out.print("a");
        System.out.print("b");
        System.out.print("c");
        System.out.print("d");
        System.out.println(" ");
    }

    public static void method2(){
        System.out.print("A");
        System.out.print("B");
        System.out.print("C");
        System.out.print("D");
        System.out.println(" ");
    }

    public static void method3(){
        System.out.print("1");
        System.out.print("2");
        System.out.print("3");
        System.out.print("4");
        System.out.println(" ");
    }
}