Java并发编程：使用CountDownLatch实现多个任务的同步协调

原创谁借莪１个温暖的怀抱￠ 2024-09-29 17:18 46阅读 0赞

在Java并发编程中，CountDownLatch是一种同步工具，它允许一个或多个线程等待其他线程完成一项工作。

以下是一个使用CountDownLatch实现多个任务同步协调的例子：

```java
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

public class CountDownLatchExample {
    private CountDownLatch countDownLatch = new CountDownLatch(3);

public void task1() {
        System.out.println("Task 1 started.");
        try {
            countDownLatch.await(5, TimeUnit.SECONDS);
            System.out.println("Task 1 completed after waiting for 5 seconds.");
        } catch (InterruptedException e) {
            System.out.println("Error occurred while waiting: " + e.getMessage());
            e.printStackTrace();
        }
    }

public void task2() {
        System.out.println("Task 2 started.");
        try {
            countDownLatch.await(10, TimeUnit.SECONDS);
            System.out.println("Task 2 completed after waiting for 10 seconds.");
        } catch (InterruptedException e) {
            System.out.println("Error occurred while waiting: " + e.getMessage());
            e.printStackTrace();
        }
    }

public void task3() {
        System.out.println("Task 3 started.");
        try {
            countDownLatch.await(5, TimeUnit.SECONDS);
            System.out.println("Task 3 completed after waiting for 5 seconds.");
        } catch (InterruptedException e) {
            System.out.println("Error occurred while waiting: " + e.getMessage());
            e.printStackTrace();
        }
    }

public static void main(String[] args) {
        CountDownLatchExample example = new CountDownLatchExample();

// 创建并启动任务线程
        new Thread(example::task1).start();
        new Thread(example::task2).start();
        new Thread(example::task3).start();
    }
}
```

在这个例子中，我们创建了三个任务（`task1`, `task2`, `task3`），每个任务在开始执行前都会向CountDownLatch发送一个信号。当CountDownLatch的计数器变为0时，等待的线程才会被唤醒继续执行后续代码。