public interface Publisher {    public void subscribe(Subscriber subscriber);    public void remove(Subscriber subscriber);    public void publish();}

import java.util.ArrayList;public class NewspaperPublisher implements Publisher {    private ArrayList<Subscriber> subscribers = new ArrayList<Subscriber>();    public void subscribe(Subscriber subscriber) {        subscribers.add(subscriber);    }        public void remove(Subscriber subscriber) {        subscribers.remove(subscriber);    }    public void publish() {        Publisher pub = new NewspaperPublisher();        for (Subscriber subscriber : subscribers) {            subscriber.receive(pub);        }    }}

public interface Subscriber {    public void receive(Publisher publication);}

public class Reader implements Subscriber {    private String name;    public Reader(String name) {        this.name = name;    }    public void receive(Publisher publication) {        System.out.println(name + " received " + publication);    }}

public class PublishSubscribeTest {    public static void main(String[] args) {        Reader reader1 = new Reader("reader 1");        Reader reader2 = new Reader("reader 2");                Publisher publisher = new NewspaperPublisher();        publisher.subscribe(reader1);        publisher.subscribe(reader2);                publisher.publish();    }}