Java并发工具：CountDownLatch应用示例

原创逃离我推掉我的手 2024-12-07 09:51 18阅读 0赞

CountDownLatch是Java并发编程中的一个工具类，主要用于协调多个线程的执行。当count为0时，会触发一个屏障，所有等待该屏障的线程都会被唤醒。

下面是一个简单的CountDownLatch应用示例：

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

public class CountDownLatchExample {
    private CountDownLatch countDownLatch;

public CountDownLatchExample(int initialCount) {
        this.countDownLatch = new CountDownLatch(initialCount);
    }

// producer thread
    public void produce() throws InterruptedException {
        for (int i = 0; i < 10; i++) {
            System.out.println("Produce: " + i);
            countDownLatch.countDown();
        }
        System.out.println("Producer done.");
    }

// consumer thread
    public void consume() throws InterruptedException {
        System.out.println("Consume start.");
        countDownLatch.await(5, TimeUnit.SECONDS)); // wait for 5 seconds or until count reaches zero

if (countDownLatch.getCount() == 0) {
            System.out.println("All consumers done.");
        } else {
            System.out.println("Some consumers still running.");
        }
    }

public static void main(String[] args) {
        CountDownLatchExample example = new CountDownLatchExample(10); // initial count is 10

new Thread(example::produce).start(); // producer thread
        new Thread(example::consume).start(); // consumer thread
    }
}
```

在这个例子中，我们创建了一个初始计数为10的CountDownLatch。生产者线程会依次执行10次任务，并使用`countDown()`方法减少计数。消费者线程会等待所有任务完成后才继续执行。