CountDownLatch

import java.util.concurrent.CountDownLatch;

 

public class TestCountDownLatch {

 

public static void main(String[] args) throws InterruptedException {

final CountDownLatch c = new CountDownLatch(2);

 

Thread th = new Thread(new Runnable(){

 

@Override

public void run() {

System.out.println(Thread.currentThread().getName()+" hello , i am so happy");

c.countDown();

System.out.println(Thread.currentThread().getName()+" hello , i am soo happy");

c.countDown();

 

}

 

}, "firstThread");

 

th.start();

c.await();

 

 

System.out.println("this is it");

}

 

}

 

 

countDownLatch 的countDown的方法时， N就减一，await 方法会阻塞当前线程， 直到N等于0；