五哲学家进餐问题java

五哲学家进餐问题是一个经典的并发编程问题，涉及到多个线程之间的同步和资源竞争。问题描述如下：五个哲学家围坐在一张圆桌前，每个哲学家面前有一碗饭和一只筷子。哲学家的生活方式非常奇特，他们交替进行思考和进餐。当一个哲学家思考时，他会放下他的两只筷子，但是当他想要进餐时，他必须同时拿起他左右两边的筷子才能吃到饭。问题在于如何避免死锁和饥饿的情况发生。

解决方案：
1. 给每个哲学家分配一个编号，编号为奇数的哲学家先拿起左边的筷子再拿右边的筷子，编号为偶数的哲学家先拿起右边的筷子再拿左边的筷子。
2. 引入一个服务员，服务员控制每个哲学家拿筷子的顺序，避免死锁和饥饿的情况发生。

Java代码实现：

public class Philosopher implements Runnable {
    private int id;
    private Object leftChopstick;
    private Object rightChopstick;

    public Philosopher(int id, Object leftChopstick, Object rightChopstick) {
        this.id = id;
        this.leftChopstick = leftChopstick;
        this.rightChopstick = rightChopstick;
    }

    public void run() {
        try {
            while (true) {
                //思考
                System.out.println("Philosopher " + id + " is thinking.");
                Thread.sleep((int) (Math.random() * 100));

                //拿起左边的筷子
                synchronized (leftChopstick) {
                    System.out.println("Philosopher " + id + " picked up left chopstick.");
                    //拿起右边的筷子
                    synchronized (rightChopstick) {
                        System.out.println("Philosopher " + id + " picked up right chopstick and is eating.");
                        //进餐
                        Thread.sleep((int) (Math.random() * 100));
                        System.out.println("Philosopher " + id + " put down right chopstick.");
                    }
                    //放下左边的筷子
                    System.out.println("Philosopher " + id + " put down left chopstick.");
                }
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

public class DiningPhilosophers {
    public static void main(String[] args) {
        Philosopher[] philosophers = new Philosopher[5];
        Object[] chopsticks = new Object[5];

        for (int i = 0; i < 5; i++) {
            chopsticks[i] = new Object();
        }

        for (int i = 0; i < 5; i++) {
            Object leftChopstick = chopsticks[i];
            Object rightChopstick = chopsticks[(i + 1) % 5];

            if (i == 4) {
                philosophers[i] = new Philosopher(i, rightChopstick, leftChopstick);
            } else {
                philosophers[i] = new Philosopher(i, leftChopstick, rightChopstick);
            }

            new Thread(philosophers[i]).start();
        }
    }
}