思路

该思路和synchronized+wait/notify方法的很像，synchronized对应lock，await/signal方法对应wait/notify方法。下面的代码为了能精准地唤醒下一个线程，创建了多个Condition对象。

代码

class LockConditionABC {
​
    private int num;
    private static Lock lock = new ReentrantLock();
    private static Condition c1 = lock.newCondition();
    private static Condition c2 = lock.newCondition();
    private static Condition c3 = lock.newCondition();
​
    private void printABC(int targetNum, Condition currentThread, Condition nextThread) {
        for (int i = 0; i < 10; ) {
            lock.lock();
            try {
                while (num % 3 != targetNum) {
                    currentThread.await();  //阻塞当前线程
                }
                num++;
                i++;
                System.out.print(Thread.currentThread().getName());
                nextThread.signal();    //唤醒下一个线程，而不是唤醒所有线程
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                lock.unlock();
            }
        }
    }
​
    public static void main(String[] args) {
        LockConditionABC print = new LockConditionABC();
        new Thread(() -> {
            print.printABC(0, c1, c2);
        }, "A").start();
        new Thread(() -> {
            print.printABC(1, c2, c3);
        }, "B").start();
        new Thread(() -> {
            print.printABC(2, c3, c1);
        }, "C").start();
    }
}