ProducerConsumerProblemBlockingQueueDemo.java

package com.codecafe.concurrency.threadsignalling;

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;

// Producer and Consumer problem
// producer produces messages at a faster rate than the consumer can consume

// Revision of the original solution - use BlockingQueue instead of using our own MessageQueue

class _Producer implements Runnable {

  BlockingQueue<String> queue;

  public _Producer(BlockingQueue<String> queue) {
    this.queue = queue;
  }

  @Override
  public void run() {
    for (int i = 1; i <= 10; i++) {
      String message = "message #" + i;
      try {
        // Inserts the specified element into this queue, waiting if necessary for space to become available
        queue.put(message);
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
      System.out.println("sent - " + message);
    }
  }

}


class _Consumer implements Runnable {

  BlockingQueue<String> queue;

  public _Consumer(BlockingQueue<String> queue) {
    this.queue = queue;
  }

  @Override
  public void run() {
    for (int i = 1; i <= 10; i++) {
      String message;
      try {
        // Retrieves and removes the head of this queue, waiting if necessary until an element becomes available
        message = queue.take();
        System.out.println("received - " + message);
      } catch (InterruptedException e) {
        e.printStackTrace();
      }
    }
  }

}


public class ProducerConsumerProblemBlockingQueueDemo {

  public static void main(String[] args) {
    // buffer limit is set to 3
    BlockingQueue<String> queue = new ArrayBlockingQueue<>(3);

    Thread producerThread = new Thread(new _Producer(queue));
    Thread consumerThread = new Thread(new _Consumer(queue));

    producerThread.start();
    consumerThread.start();
  }

}