CountDownLatch实现线程让领导先行

最新推荐文章于 2024-06-17 20:36:43 发布

原创最新推荐文章于 2024-06-17 20:36:43 发布 · 183 阅读

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本文通过一个火灾逃生场景的代码示例，演示了如何使用Java并发工具包中的CountDownLatch来协调多线程操作，确保所有军官先行撤离后再允许普通民众离开，展示了CountDownLatch在控制线程同步中的应用。

CountDownLatch latch = new CountDownLatch(OFFICER_SIZE);//初始化计数器
latch.countDown();//计数器减一
latch.await();// 等待计数器为零

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class LatchDemo {
    public static final int OFFICER_SIZE = 80;// 0000000;

    public static final int COMMON_PEOPLE_SIZE = 20;

    public static void main(String[] args) {
        ExecutorService exeuctor = Executors.newCachedThreadPool();
        // must share the single latch
        CountDownLatch latch = new CountDownLatch(OFFICER_SIZE);
        System.out.println("the building is fire!");

        for (int i = 0; i < COMMON_PEOPLE_SIZE; i++) {
            exeuctor.execute(new commonPeople(i, latch));
        }

        for (int i = 0; i < OFFICER_SIZE; i++) {
            exeuctor.execute(new officer(i, latch));
        }
        exeuctor.shutdown();
    }

    static class officer implements Runnable {
        private int id;

        private CountDownLatch latch;

        public officer(int id, CountDownLatch latch) {
            this.id = id;
            this.latch = latch;
        }

        @Override
        public void run() {
            goOut();
            latch.countDown();
        }

        private void goOut() {
            System.out.println("I must go firstly when fire! my id:" + id);
        }
    }

    static class commonPeople implements Runnable {
        private int id;

        private CountDownLatch latch;

        public commonPeople(int id, CountDownLatch latch) {
            this.id = id;
            this.latch = latch;
        }

        @Override
        public void run() {
            try {
                latch.await();
                goOut();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        private void goOut() {
            System.out.println("I am common people! my id:" + id);
        }
    }

}