Producer Consumer Problem using Synchronized block

• If List is full then our PRODUCER thread waits until CONSUMER thread consume one item and make space in your queue and call notify() method to inform PRODUCER thread. Both wait() and notify() method are called on shared object which is List in our case.
• Need synchronised block
• Check for List size manually and wait for consumer and producer threads
• Since it is synchronised,
• Needs to wait till N production
• Needs to wait till N Consumption
• Producer.java
• public class Producer implements Runnable { private static List LIST; private static int SIZE; public Producer(List LIST_V, int SIZE_V) { LIST = LIST_V; SIZE = SIZE_V; } public void run() { producer(); } private static void producer() { try { int i = 1; while (true) { synchronized (LIST) { if (LIST.size() == SIZE) { System.out.println("Producer Waiting for consumer to consume object"); LIST.wait(); } LIST.add(i); System.out.println(i + " Produced"); LIST.notify(); } i++; if (i > 100) { break; } } } catch (Exception e) { e.printStackTrace(); } } }
• Consumer.java
• public class Consumer implements Runnable { private static List LIST; public Consumer(List LIST_V) { LIST = LIST_V; } public void run() { consumer(); } private static void consumer() { int index = 0; try { Thread.sleep(2000); while (true) { synchronized (LIST) { if (LIST.size() == 0) { System.out.println("Consumer is waiting for producer to produce"); LIST.wait(); } System.out.println(LIST.get(index) + " Consumed"); LIST.remove(index); LIST.notify(); } } } catch (Exception e) { e.printStackTrace(); } } }
• App.java
• public class App { private static List LIST = new ArrayList(); private static int SIZE = 10; public static void main(String[] args) { Thread producer = new Thread(new Producer(LIST, SIZE)); Thread consumer = new Thread(new Consumer(LIST)); producer.start(); consumer.start(); } }
• Output
• 1 Produced 2 Produced 3 Produced 4 Produced 5 Produced 6 Produced 7 Produced 8 Produced 9 Produced 10 Produced Producer Waiting for consumer to consume object 1 Consumed 2 Consumed 3 Consumed 4 Consumed 5 Consumed 6 Consumed 7 Consumed 8 Consumed 9 Consumed 10 Consumed Consumer is waiting for producer to produce 11 Produced 12 Produced 13 Produced