Java - Threads Part 4: Thread Communication

Threads can communicate using methods like wait(), notify(), and notifyAll().

Examples and Explanation

Wait and Notify

class SharedResource {

    public synchronized void produce() throws InterruptedException {

        System.out.println("Producing...");

        wait();

        System.out.println("Resumed!");

    }

    public synchronized void consume() {

        System.out.println("Consuming...");

        notify();

    }

}

public class Main {

    public static void main(String[] args) {

        SharedResource resource = new SharedResource();

        Thread producer = new Thread(() -> {

            try {

                resource.produce();

            } catch (InterruptedException e) {

                e.printStackTrace();

            }

        });

        Thread consumer = new Thread(resource::consume);

        producer.start();

        consumer.start();

    }

}

Explanation: wait() pauses the thread until another thread calls notify().

Using notifyAll()

public synchronized void notifyAllThreads() {

    notifyAll();

}

Explanation: This method wakes all threads waiting on an object's monitor.