深入理解：Java多线程并发问题示例-蒲公英云

深入理解：Java多线程并发问题示例

在Java中，多线程并发问题是编程中的常见挑战。主要涉及以下几种问题：

死锁：多个线程相互等待对方释放资源，导致所有线程都无法继续执行。

示例：

class Resource {
    boolean locked;
    Resource() { locked = false; }
}
class ThreadA implements Runnable {
    Resource res;
    ThreadA(Resource res) { this.res = res; }
    @Override
    public void run() {
        res.locked = true;
        try {
            System.out.println("Thread A: waiting...");
            // 线程B等待ThreadA释放资源
            Thread.sleep(500);
        } finally {
            res.locked = false;
            System.out.println("Thread A: released resources");
        }
    }
}
class ThreadB implements Runnable {
    Resource res;
    ThreadB(Resource res) { this.res = res; }
    @Override
    public void run() {
        res.locked = true;
        try {
            System.out.println("Thread B: waiting for A...");
            // 线程A释放资源后，线程B尝试获取资源
            Thread.sleep(2000);
        } finally {
            res.locked = false;
            System.out.println("Thread B: released resources");
        }
    }
}
public class Main {
    public static void main(String[] args) {
        Resource res = new Resource();
        ThreadA threadA = new ThreadA(res);
        ThreadB threadB = new ThreadB(res);
        // 启动线程
        new Thread(threadA).start();
        new Thread(threadB).start();
        System.out.println("Main: exiting...");
    }
}