Java 8 - juc - CountDownLatch

缺乏、安全感 2023-10-11 22:42 32阅读 0赞

import java.util.concurrent.CountDownLatch;
    
    /**
     * 当使用CountDownLatch时，需要指定等待的线程数量。
     * 每个线程在执行完特定操作后，调用countDown()方法通知CountDownLatch计数器减少一个。
     * 主线程可以通过调用await()方法等待所有线程完成操作。
     *
     * CountDownLatch的计数器不能重新设置。如果需要重新使用CountDownLatch，需要创建一个新的实例。
     */
    public class MyCountDownLatchExample {
        
        public static void main(String[] args) {
        
            // 指定等待的线程数量为3
            CountDownLatch latch = new CountDownLatch(3);
    
            // 创建并启动三个线程
            Thread thread1 = new Thread(new Worker1(latch, "Worker 1"));
            Thread thread2 = new Thread(new Worker1(latch, "Worker 2"));
            Thread thread3 = new Thread(new Worker1(latch, "Worker 3"));
    
            thread1.start();
            thread2.start();
            thread3.start();
    
            try {
        
                // 主线程等待所有线程执行完操作
                latch.await();
                System.out.println("All workers have completed their tasks.");
            } catch (InterruptedException e) {
        
                e.printStackTrace();
            }
        }
    }
    
    class Worker1 implements Runnable {
        
        private final CountDownLatch latch;
        private final String name;
    
        public Worker1(CountDownLatch latch, String name) {
        
            this.latch = latch;
            this.name = name;
        }
    
        @Override
        public void run() {
        
            System.out.println(name + " is performing task.");
            // 模拟工作
            try {
        
                Thread.sleep(2000);
            } catch (InterruptedException e) {
        
                e.printStackTrace();
            }
            System.out.println(name + " has completed task.");
            // 通知CountDownLatch计数器减少一个
            latch.countDown();
        }
    }