Java多线程同步问题：Lock接口与Synchronized关键字的对比示例

原创小灰灰 2024-11-23 14:00 23阅读 0赞

在Java中，多线程同步主要依赖于Lock接口和synchronized关键字。下面我们将通过一个简单的示例来对比它们：

1. 使用synchronized关键字：
```java
public class SynchronizedExample {
    private int count = 0;

public synchronized void increment() {
        count++;
    }

public synchronized int getCount() {
        return count;
    }

public static void main(String[] args) {
        SynchronizedExample example = new SynchronizedExample();
        Thread thread1 = new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                example.increment();
            }
        })));

Thread thread2 = new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                System.out.println("Thread 2: " + example.getCount());
            }
        })));

thread1.start();
        thread2.start();

// 等待所有线程完成
        thread1.join();
        thread2.join();

System.out.println("Final count: " + example.getCount());
    }
}
```
2. 使用Lock接口：
```java
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public class LockExample {
    private int count = 0;
    private Lock lock = new ReentrantLock();

public void increment() {
        lock.lock();
        try {
            count++;
        } finally {
            lock.unlock();
        }
    }

public int getCount() {
        return count;
    }

public static void main(String[] args) {
        LockExample example = new LockExample();
        Thread thread1 = new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                example.increment();
            }
        })));

Thread thread2 = new Thread(() -> {
            for (int i = 0; i < 5; i++) {
                System.out.println("Thread 2: " + example.getCount()));
            }
        })));

thread1.start();
        thread2.start();

// 等待所有线程完成
        thread1.join();
        thread2.join();

System.out.println("Final count: " + example.getCount()));
    }
}
```
总结：

- synchronized关键字实现的是基于对象的锁，适用于代码相对较少的情况。
- Lock接口提供了更灵活的多线程同步方式，适用于复杂多线程场景。

在实际项目中，可以根据需求和代码规模选择合适的同步方式。