java - java中使用对象锁实现同步

Question

我有两个线程 thread1(打印数字)和 thread2(打印字母)。我的目标是通过同步获得以下输出:

1 a 2 b 3 c 4 d 5 e

class thread1 implements Runnable {
    public void run() {

        try {

            for (int i = 1; i <= 5; i++) {
                System.out.println("Is Thread1 holding lock of Testing.class?:"+Thread.holdsLock(Testing.class));
                synchronized (Testing.class) {
                    System.out.println("Is Thread1 holding lock of Testing.class?:"+Thread.holdsLock(Testing.class));

                    try {
                        System.out.println(i);
                        Testing.class.notifyAll();
                        System.out.println("Thread1:Going to wait");
                        Testing.class.wait();
                        System.out.println("Thread1:Resuming from wait");
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }

            }

            System.out.println("Finsihed thread1");


        } catch (Exception e) {
            System.out.println(e);
        }

    }
}



class thread2 implements Runnable {
    char[] alphabets = { 'a', 'b', 'c', 'd', 'e' };

    public void run() {

        try {

            for (int i = 0; i < 5; i++) {
                System.out.println("Is Thread2 holding lock of Testing.class?:"+Thread.holdsLock(Testing.class));
                synchronized (Testing.class) {
                    try {
                        System.out.println("Is Thread2 holding lock of Testing.class?:"+Thread.holdsLock(Testing.class));
                        System.out.println("Thread2:Going to wait");
                        Testing.class.wait();
                        System.out.println("Thread2:Resuming from wait");
                        System.out.println(alphabets[i]);
                        Testing.class.notifyAll();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }


        } catch (Exception e) {
            System.out.println(e);
        }

    }

}


    public class Testing {

        public static void main(String[] args) {
            Testing w= new Testing();
            thread1 t1 = new thread1();
            thread2 t2 = new thread2();
            Thread th1 = new Thread(t1, "");

            Thread th2 = new Thread(t2, "");
            try {
                th1.start();
                th2.start();
            } catch (Exception e) {
                System.out.println(e);
            }

        }
    }

我正在获取输出:

Is Thread1 holding lock of Testing.class?:false

Is Thread1 holding lock of Testing.class?:true

1

Thread1:Going to wait

Is Thread2 holding lock of Testing.class?:false

Is Thread2 holding lock of Testing.class?:true

Thread2:Going to wait

当 Testing.class 已经被 thread1 锁定时，thread2 是如何获得锁的？另外，还有其他优雅的方式来实现这种同步吗？提前致谢。

Answer 1

阅读更多关于 Java Concurrency 的信息.

调用 wait 释放锁。