dining_philosopher.java

import java.util.concurrent.Semaphore;
import java.util.concurrent.ThreadLocalRandom;

public class dining_philosopher {

    static int philosopher = 5;
    static Philosopher philosophers[] = new Philosopher[philosopher];
    static Chopstick chopsticks[] = new Chopstick[philosopher];
    
    static class Chopstick {

        public Semaphore mutex = new Semaphore(1);

        void grab() {
            try {

                mutex.acquire();
            } catch (Exception e) {
                e.printStackTrace(System.out);
            }
        }

        void release() {

            mutex.release();
        }

        boolean isFree() {

            return mutex.availablePermits() > 0;
        }
    }

    static class Philosopher extends Thread {
        public int number;

        public Chopstick leftchopstick;

        public Chopstick rightchopstick;

        Philosopher(int num, Chopstick left, Chopstick right) {
            number = num;
            leftchopstick = left;
            rightchopstick = right;
        }

        public void run() {
            while (true) {

                leftchopstick.grab();
                System.out.println("Philosopher " + (number + 1) + " grabs left chopstick.");
                rightchopstick.grab();
                System.out.println("Philosopher " + (number + 1) + " grabs right chopstick.");

                eat();

                leftchopstick.release();
                System.out.println("Philosopher " + (number + 1) + " releases left chopstick.");
                rightchopstick.release();
                System.out.println("Philosopher " + (number + 1) + " releases right chopstick.");
            }
        }

        void eat() {
            try {

                int sleepTime = ThreadLocalRandom.current().nextInt(0, 1000);
                System.out.println("Philosopher " + (number + 1) + " eats for " + sleepTime + "ms");
                Thread.sleep(sleepTime);
            } catch (Exception e) {
                e.printStackTrace(System.out);
            }
        }
    }

    public static void main(String args[]) {

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

        for (int i = 0; i < philosopher; i++) {
            philosophers[i] = new Philosopher(i, chopsticks[i], chopsticks[(i + 1) % philosopher]);

            philosophers[i].start();
        }
        while (true) {
            try {

                Thread.sleep(1000);

                boolean deadlock = true;

                for (Chopstick cs : chopsticks) {

                    if (cs.isFree()) {
                        deadlock = false;
                        break;
                    }
                }

                if (deadlock) {
                    Thread.sleep(1000);
                    System.out.println("Everyone Eats");
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace(System.out);
            }
        }
        System.out.println("Exit The Program!");
        System.exit(0);
    }
}