用Java写上面这个问题

在Java中，我们可以使用`java.util.concurrent`包下的`ExecutorService`和`Future`来创建线程池，并结合`CountDownLatch`来控制线程的执行顺序，以便线程A和线程B交替输出。以下是使用Java实现的版本：

import java.util.concurrent.*;

public class ThreadDemo {
    private static final int COUNT_DOWN = 1000;

    public static void main(String[] args) throws InterruptedException {
        ExecutorService executor = Executors.newFixedThreadPool(2);
        CountDownLatch startLatch = new CountDownLatch(2);
        Future<?> futureA = executor.submit(new OutputThread("A", startLatch, COUNT_DOWN));
        Future<?> futureB = executor.submit(new OutputThread("B", startLatch, COUNT_DOWN));

        startLatch.await(); // 等待两个任务都启动
        executor.shutdown(); // 关闭线程池

        futureA.get(); // 阻塞等待A完成
        futureB.get(); // 阻塞等待B完成
    }

    static class OutputThread implements Runnable {
        private final String name;
        private final CountDownLatch startLatch;
        private final int countDown;

        public OutputThread(String name, CountDownLatch startLatch, int countDown) {
            this.name = name;
            this.startLatch = startLatch;
            this.countDown = countDown;
        }

        @Override
        public void run() {
            try {
                startLatch.countDown(); // 启动信号，允许另一个线程开始
                while (countDown > 0) {
                    System.out.printf("[%s] %d,%n", name, --countDown);
                    Thread.sleep(200); // 模拟0.2秒间隔
                }
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
        }
    }
}