理解CountDownLatch

最新推荐文章于 2025-11-15 21:15:42 发布

最新推荐文章于 2025-11-15 21:15:42 发布 · 101 阅读

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本文通过一个测试类实例详细介绍了CountDownLatch类的使用方法及其在Java并发编程中的作用。通过CountDownLatch，可以实现线程间的等待-继续机制，即主线程等待其他线程完成指定操作后再继续执行。

字面意思是倒计时类
类名其实说的很形象，倒数到0时线程解除阻塞，继续往下执行

测试类
public class TestCDL {
private static CountDownLatch countDownLatch = new CountDownLatch(3);

public static void test(){

Thread thread = new Thread(){
@Override
public void run() {
try {
//阻塞在这儿了
countDownLatch.await();
} catch (InterruptedException e) {
e.printStackTrace();
}finally{
System.out.println("after await" + this.getId());
}
}
};

thread.start();

//count = 3
System.out.println("Count:" + countDownLatch.getCount());
countDownLatch.countDown();

//count = 2
System.out.println("Count:" + countDownLatch.getCount());

countDownLatch.countDown();
countDownLatch.countDown();

//count = 0 ；线程解除了阻塞
System.out.println("Count:" + countDownLatch.getCount());
}

public static void main(String[] args) {
test();
}
}