package com.smart.thread;

import java.util.LinkedList;
import java.util.Queue;
import java.util.Random;
/**

• Simple Java program to demonstrate How to use wait, notify and notifyAll()
• method in Java by solving producer consumer problem.
• @author Javin Paul
  */
  public class ProducerConsumerInDemo {
  public static void main(String args[]) {
  System.out.println("How to use wait and notify method in Java");
  System.out.println("Solving Producer Consumer Problem");
  Queue<Integer> buffer = new LinkedList<Integer>();
  int maxSize = 10;
  Thread producer = new Producer(buffer, maxSize, "PRODUCER");
  Thread consumer = new Consumer(buffer, maxSize, "CONSUMER");
  producer.start();
  consumer.start();
  }
  }

/**

• Producer Thread will keep producing values for Consumer
• to consumer. It will use wait() method when Queue is full
• and use notify() method to send notification to Consumer
• Thread.
• @author WINDOWS 8

*/
class Producer extends Thread {
private final Queue<Integer> queue;
private int maxSize;
public Producer(Queue<Integer> queue, int maxSize, String name){
super(name);
this.queue = queue;
this.maxSize = maxSize;
}

@Override
public void run() {
    while (true) {
        synchronized (queue) {
            while (queue.size() == maxSize) {
                try {
                    System.out .println("Queue is full, " + "Producer thread waiting for " + "consumer to take something from queue");
                    queue.wait();
                } catch (Exception ex) {
                    ex.printStackTrace(); }
            }
            Random random = new Random();
            int i = random.nextInt();
            System.out.println("Producing value : " + i);
            queue.add(i);
            queue.notify();
        }
    }
}

}

/**

• Consumer Thread will consumer values form shared queue.
• It will also use wait() method to wait if queue is
• empty. It will also use notify method to send
• notification to producer thread after consuming values
• from queue.
• @author WINDOWS 8

*/
class Consumer extends Thread {
private final Queue<Integer> queue;
public Consumer(Queue<Integer> queue, int maxSize, String name){
super(name);
this.queue = queue;
}

@Override
public void run() {
    while (true) {
        synchronized (queue) {
            while (queue.isEmpty()) {
                System.out.println("Queue is empty," + "Consumer thread is waiting" + " for producer thread to put something in queue");
                try {
                    queue.wait();
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
            System.out.println("Consuming value : " + queue.remove());
            queue.notify();
        }
    }
}

}