public class ABC_Lock { private static Lock lock = new ReentrantLock();// 通过JDK5中的Lock锁来保证线程的访问的互斥 private static int state = 0;//通过state的值来确定是否打印 static class ThreadA extends Thread { @Override public void run() { for (int i = 0; i < 10;) { try { lock.lock(); while (state % 3 == 0) {// 多线程并发,不能用if,必须用循环测试等待条件,避免虚假唤醒 System.out.print("A"); state++; i++; } } finally { lock.unlock();// unlock()操作必须放在finally块中 } } } } static class ThreadB extends Thread { @Override public void run() { for (int i = 0; i < 10;) { try { lock.lock(); while (state % 3 == 1) {// 多线程并发,不能用if,必须用循环测试等待条件,避免虚假唤醒 System.out.print("B"); state++; i++; } } finally { lock.unlock();// unlock()操作必须放在finally块中 } } } } static class ThreadC extends Thread { @Override public void run() { for (int i = 0; i < 10;) { try { lock.lock(); while (state % 3 == 2) {// 多线程并发,不能用if,必须用循环测试等待条件,避免虚假唤醒 System.out.print("C"); state++; i++; } } finally { lock.unlock();// unlock()操作必须放在finally块中 } } } } public static void main(String[] args) { new ThreadA().start(); new ThreadB().start(); new ThreadC().start(); } }