CountDownLatch

最新推荐文章于 2022-04-30 21:21:49 发布

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本文展示了如何在Java中使用CountDownLatch和Thread.join()进行多线程同步。通过示例代码，解释了CountDownLatch如何倒计时等待所有线程完成任务，以及join()方法如何让主线程等待子线程执行完毕。这两个工具在多线程编程中常用于协调线程间的操作。

                                  CountDownLatch

package com.qqjx.thread;


import java.util.concurrent.CountDownLatch;
/*
 * @Auther  wangpeng
 * @Date 2021/1/15
 * */

public class T06_TestCountDownLatch {

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

    private static void usingCountDownLatch() {
        Thread[] threads = new Thread[100];
        CountDownLatch latch = new CountDownLatch(threads.length);

        for(int i=0; i<threads.length; i++) {
            threads[i] = new Thread(()->{
                int result = 0;
                for(int j=0; j<10000; j++) result += j;
                latch.countDown();
            });
        }

        for (int i = 0; i < threads.length; i++) {
            threads[i].start();
        }

        try {
            latch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println("end latch");
    }

    private static void usingJoin() {
        Thread[] threads = new Thread[100];

        for(int i=0; i<threads.length; i++) {
            threads[i] = new Thread(()->{
                int result = 0;
                for(int j=0; j<10000; j++) result += j;
            });
        }

        for (int i = 0; i < threads.length; i++) {
            threads[i].start();
        }

        for (int i = 0; i < threads.length; i++) {
            try {
                threads[i].join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        System.out.println("end join");
    }



}

end join
end latch