锁的小练习

使用 synchronized 关键字的示例

class SynchronizedCounter {
    private int count = 0;

    // 使用 synchronized 方法
    public synchronized void increment() {
        count++;
    }

    public int getCount() {
        return count;
    }
}

public class SynchronizedExample {
    public static void main(String[] args) throws InterruptedException {
        SynchronizedCounter counter = new SynchronizedCounter();
        
        // 创建多个线程
        Thread t1 = new Thread(() -> {
            for (int i = 0; i < 1000; i++) {
                counter.increment();
            }
        });

        Thread t2 = new Thread(() -> {
            for (int i = 0; i < 1000; i++) {
                counter.increment();
            }
        });

        // 启动线程
        t1.start();
        t2.start();
        // 等待线程完成
        t1.join();
        t2.join();

        // 输出结果
        System.out.println("Final count: " + counter.getCount()); // 应该输出 2000
    }
}

reentrant:

import java.util.concurrent.locks.ReentrantLock;

class ReentrantLockCounter {
    private int count = 0;
    private final ReentrantLock lock = new ReentrantLock();

    public void increment() {
        lock.lock(); // 加锁
        try {
            count++;
        } finally {
            lock.unlock(); // 确保释放锁
        }
    }

    public int getCount() {
        return count;
    }
}

public class ReentrantLockExample {
    public static void main(String[] args) throws InterruptedException {
        ReentrantLockCounter counter = new ReentrantLockCounter();
        
        // 创建多个线程
        Thread t1 = new Thread(() -> {
            for (int i = 0; i < 1000; i++) {
                counter.increment();
            }
        });

        Thread t2 = new Thread(() -> {
            for (int i = 0; i < 1000; i++) {
                counter.increment();
            }
        });

        // 启动线程
        t1.start();
        t2.start();
        // 等待线程完成
        t1.join();
        t2.join();//诸塞线程，知道它执行完

        // 输出结果
        System.out.println("Final count: " + counter.getCount()); // 应该输出 2000
    }
}