Java中CountDownLatch工具类详细解析

CountDownLatch countDownLatch = new CountDownLatch(4); //初始 count = 4
countDownLatch.countDown(); // count = 4 -1;
countDownLatch.countDown();  // count = 3-1;
countDownLatch.await(); //当count =0 ，可以执行后续代码

import java.util.concurrent.CountDownLatch;

public class Test {

    public static void main(String[] args) throws InterruptedException {
        CountDownLatch countDownLatch = new CountDownLatch(5);

        new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println(Thread.currentThread().getName()+"已运行!");
                countDownLatch.countDown();
            }
        }).start();

        countDownLatch.await();
        System.out.println(" 程序执行完毕! ");
    }
}

import java.util.concurrent.CountDownLatch;

public class Test1 {

    public static void main(String[] args) throws InterruptedException {
        CountDownLatch countDownLatch = new CountDownLatch(5);
        for(int i = 0 ; i < 5 ; i++){
            new Thread(new Runnable() {
                @Override
                public void run() {
                    System.out.println(Thread.currentThread().getName()+"已运行!");
                    countDownLatch.countDown();
                }
            }).start();
        }


        countDownLatch.await();
        System.out.println(" 程序执行完毕! ");
    }
}