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Description:
  yasmin
Language: JAVA
Code:
p/* executed on coding ground
Output:
Produced: 0
Queue is empty Consumer is waiting , size: 0
Produced: 1
Consumed: 0
Produced: 2
Produced: 3
Produced: 4
Produced: 5
Queue is full Producer is waiting , size: 4
Consumed: 1
Produced: 6
Queue is full Producer is waiting , size: 4
Consumed: 2
Consumed: 3
Consumed: 4
Consumed: 5
Consumed: 6
Queue is empty Consumer is waiting , size: 0 */


import java.util.Vector;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * Java program to solve Producer Consumer problem using wait and notify
 * method in Java. Producer Consumer is also a popular concurrency design pattern.
 *
 * @author Javin Paul
 */
public class ProducerConsumerSolution {

    public static void main(String args[]) {
        Vector sharedQueue = new Vector();
        int size = 4;
        Thread prodThread = new Thread(new Producer(sharedQueue, size), "Producer");
        Thread consThread = new Thread(new Consumer(sharedQueue, size), "Consumer");
        prodThread.start();
        consThread.start();
    }
}

class Producer implements Runnable {

    private final Vector sharedQueue;
    private final int SIZE;

    public Producer(Vector sharedQueue, int size) {
        this.sharedQueue = sharedQueue;
        this.SIZE = size;
    }

    @Override
    public void run() {
        for (int i = 0; i < 7; i++) {
            System.out.println("Produced: " + i);
            try {
                produce(i);
            } catch (InterruptedException ex) {
                Logger.getLogger(Producer.class.getName()).log(Level.SEVERE, null, ex);
            }

        }
    }

    private void produce(int i) throws InterruptedException {

        //wait if queue is full
        while (sharedQueue.size() == SIZE) {
            synchronized (sharedQueue) {
                System.out.println("Queue is full " + Thread.currentThread().getName()
                                    + " is waiting , size: " + sharedQueue.size());

                sharedQueue.wait();
            }
        }

        //producing element and notify consumers
        synchronized (sharedQueue) {
            sharedQueue.add(i);
            sharedQueue.notifyAll();
        }
    }
}

class Consumer implements Runnable {

    private final Vector sharedQueue;
    private final int SIZE;

    public Consumer(Vector sharedQueue, int size) {
        this.sharedQueue = sharedQueue;
        this.SIZE = size;
    }

    @Override
    public void run() {
        while (true) {
            try {
                System.out.println("Consumed: " + consume());
                Thread.sleep(50);
            } catch (InterruptedException ex) {
                Logger.getLogger(Consumer.class.getName()).log(Level.SEVERE, null, ex);
            }

        }
    }

    private int consume() throws InterruptedException {
        //wait if queue is empty
        while (sharedQueue.isEmpty()) {
            synchronized (sharedQueue) {
                System.out.println("Queue is empty " + Thread.currentThread().getName()
                                    + " is waiting , size: " + sharedQueue.size());

                sharedQueue.wait();
            }
        }

        //Otherwise consume element and notify waiting producer
        synchronized (sharedQueue) {
            sharedQueue.notifyAll();
            return (Integer) sharedQueue.remove(0);
        }
    }
}
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