多线程同步挑战：Java并发工具类使用示例

原创阳光穿透心脏的1/2处 2024-11-27 07:24 56阅读 0赞

在Java中，多线程同步是非常重要的一部分，主要是为了避免数据的不一致。以下是一些常用的Java并发工具类以及使用示例：

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

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

public synchronized int decrementIfExist() {
        if (count > 0) {
            count--;
            return count;
        } else {
            return count; // 没有减成功，直接返回原值
        }
    }

public synchronized int getCount() {
        return count;
    }
}
```
2. **Lock接口（如ReentrantLock）**：
```java
import java.util.concurrent.locks.Lock;

public class LockDemo {
    private final Lock lock = new ReentrantLock();

public void criticalSection() {
        lock.lock(); // 获取锁

try {
            System.out.println("Critical section is executing...");

// 执行需要同步的代码...

} finally {
            lock.unlock(); // 释放锁
        }
    }

public static void main(String[] args) {
        LockDemo demo = new LockDemo();

Thread thread1 = new Thread(() -> {
            System.out.println("Thread 1 starting critical section...");

demo.criticalSection();

System.out.println("Thread 1 exiting critical section...");
        }));

Thread thread2 = new Thread(() -> {
            System.out.println("Thread 2 starting critical section...");

demo.criticalSection();

System.out.println("Thread 2 exiting critical section...");
        }));

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

// 程序执行完毕后，可以释放锁
        // 这里不需要手动释放锁，因为Java的垃圾回收机制会自动管理锁
    }
}
```
3. **Condition接口（如ConcurrentLinkedQueue）**：
```java
import java.util.concurrent.locks.Condition;

public class ConditionDemo {
    private final Lock lock = new ReentrantLock();
    private final Condition condition = lock.newCondition();

public void criticalSection() throws InterruptedException {
        lock.lock(); // 获取锁

try {
            System.out.println("Critical section is executing...");

// 确保只有在满足特定条件的情况下，才会执行代码...

// 假设需要等待某个事件发生，可以使用condition
            condition.await(); // 等待某个条件满足

// 执行需要同步的代码...

} finally {
            lock.unlock(); // 释放锁
        }
    }

public static void main(String[] args) {
        ConditionDemo demo = new ConditionDemo();

Thread thread1 = new Thread(() -> {
            System.out.println("Thread 1 starting critical section...");

demo.criticalSection();

System.out.println("Thread 1 exiting critical section...");
        }));

Thread thread2 = new Thread(() -> {
            System.out.println("Thread 2 starting critical section...");