antibody：public static void main(String[] args) throws InterruptedException {     final int PRINT_TIMES = 3;     final int THREADS_NUMBER = 4;     CountDownLatch latch = new CountDownLatch(THREADS_NUMBER);     Object[] locks = new Object[THREADS_NUMBER];     for (int i = 0; i < locks.length; i++) {         locks[i] = new Object();     }     for (int i = 0; i < locks.length; i++) {         new MyThread(locks[i], locks[(i + 1) % locks.length],                      PRINT_TIMES, (char) ('A' + i), latch)                 .start();     }     // 确认所有子线程已处于等待状态     latch.await();     synchronized (locks[0]) {         locks[0].notify();     } } private static class MyThread extends Thread {     final Object lock;     final Object nextLock;     int printTime;     char c;     CountDownLatch latch;     MyThread(Object lock, Object nextLock, int printTime,              char c, CountDownLatch latch) {         this.lock = lock;         this.nextLock = nextLock;         this.printTime = printTime;         this.latch = latch;         this.c = c;     }     public void run() {         synchronized (lock) {             for (int i = 0; i < printTime; i++) {                 latch.countDown();                 try {                     // 等待当前线程被唤醒                     lock.wait();                 } catch (InterruptedException e) {                     e.printStackTrace();                 }                 // 输出并唤醒下一线程                 System.out.println(c);                 synchronized (nextLock) {                     nextLock.notify();                 }             }         }         synchronized (nextLock) {             nextLock.notify();         }     } }