Classes that produce and consume data from a shared store to demonstrate the wait/notify mechanism.

WaitNotifyMechanism.java

import java.util.ArrayList;

/**
 * Classes that produce and consume data from a shared store to demonstrate the wait/notify mechanism.
 */
public class WaitNotifyMechanism {

    static ArrayList<Integer> dataStore = new ArrayList<Integer>();

    static class Producer extends Thread {

        public Producer(String name) {
            this.setName(name);
        }

        public void run() {
            while (true) {
                synchronized (dataStore) {
                    while (!dataStore.isEmpty()) {
                        System.out.printf("%s waiting for data to be empty...%n", this.getName());
                        try {
                            dataStore.wait();
                        } catch (InterruptedException ie) {
                            System.out.printf("%s interrupted while waiting!%n", this.getName());
                        }
                    }
                    System.out.printf("%s producing data...%n", this.getName());
                    try {
                        sleep(5000);
                    } catch (InterruptedException ie) {
                        System.out.printf("%s interrupted while producing data!%n", this.getName());
                    }
                    Integer newData = new Integer((int) (Math.random()*5000));
                    System.out.printf("%s produced: %d%n", this.getName(), newData);
                    dataStore.add(newData);
                    dataStore.notifyAll();
                    System.out.printf("%s done!%n", this.getName());
                }
            }
        }
    }

    static class Consumer extends Thread {

        public Consumer(String name) {
            this.setName(name);
        }

        public void run() {
            while(true) {
                synchronized (dataStore) {
                    while (dataStore.isEmpty()) {
                        System.out.printf("%s waiting for data...%n", this.getName());
                        try {
                            dataStore.wait();
                        } catch (InterruptedException ie) {
                            System.out.printf("%s interrupted while waiting!%n", this.getName());
                        }
                    }
                    System.out.printf("%s consuming data...%n", this.getName());
                    try {
                        sleep(5000);
                    } catch (InterruptedException ie) {
                        System.out.printf("%s interrupted while producing data!%n", this.getName());
                    }
                    Integer theData = dataStore.remove(0);
                    System.out.printf("%s got: %d%n", this.getName(), theData);
                    dataStore.notifyAll();
                    System.out.printf("%s done!%n", this.getName());
                }
            }
        }
    }

    public static void main(String[] args) {
        new Consumer("Cons1").start();
        new Consumer("Cons2").start();
        new Producer("Prod1").start();
    }
}