Java并发编程问题：CountDownLatch使用示例-蒲公英云

Java并发编程问题：CountDownLatch使用示例

原创秒速五厘米 2024-12-07 20:51 145阅读 0赞

CountDownLatch是Java并发工具类之一，用于协调多个线程。当一个线程到达CountDownLatch的down方法（将计数器值减1），而其他等待该事件的线程在count <= 0时会进入wait状态。

下面是一个简单的CountDownLatch使用示例：

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
public class CountDownLatchExample {
    private CountDownLatch countDownLatch = new CountDownLatch(3);
    public void thread1() {
        System.out.println("Thread 1 started");
        try {
            countDownLatch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Thread 1 finished");
    }
    public void thread2() {
        System.out.println("Thread 2 started");
        // 第一个线程已经调用了await，所以这里直接down
        countDownLatch.countDown();
        try {
            countDownLatch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Thread 2 finished");
    }
    public static void main(String[] args) {
        CountDownLatchExample example = new CountDownLatchExample();
        Thread thread1 = new Thread(example::thread1);
        Thread thread2 = new Thread(example::thread2);
        // 启动两个线程
        thread1.start();
        thread2.start();
        // 等待所有线程执行完毕
        thread1.join();
        thread2.join();
        System.out.println("All threads finished");
    }
}