ObserverAssigment

import java.util.ArrayList;

import javax.swing.CellRendererPane;

interface Subject
{
    public void register(Observer reg);
    public void unregister(Observer unreg);
    public void notifyAllObservers(String notif);
}
interface Observer
{
    public void update(String name, String s);
}

class Celebrity implements Subject
{
    private String celebrityName;
    private ArrayList<Observer> followers;

    public Celebrity(String celebrityName)
    {
        this.celebrityName = celebrityName;
        followers = new ArrayList<Observer>();
    }

    @Override
    public void register(Observer reg)
    {
        followers.add(reg);
        System.out.println(reg + " has started following " + celebrityName);
    }

    @Override
    public void unregister(Observer unreg)
    {
        followers.remove(unreg);
        System.out.println(unreg + " has stopped following " + celebrityName);
    }

    @Override
    public void notifyAllObservers(String notif)
    {
        for(Observer follower : followers)
        {
            follower.update(celebrityName, notif);
        }
        System.out.println("");
    }

    public void tweet(String tweet)
    {
        System.out.println("\n" + celebrityName + " has tweeted :: " + tweet + "\n");
        notifyAllObservers(tweet);
    }
}

class Follower implements Observer
{
    private String followerName;

    public Follower(String followerName)
    {
        this.followerName = followerName;
    }

    @Override
    public void update(String celecrityName, String tweet)
    {
        System.out.println(followerName + " has received " + celecrityName + "'s tweet :: " + tweet);
    }

    public String toString()
    {
        return followerName;
    }


}
public class test {
    public static void main(String[] args)
    {
        Celebrity ustKhalid = new Celebrity("Khalid");
        Celebrity ustFiranda = new Celebrity("Firanda");

        Follower rahmad = new Follower("Rahmad");
        Follower andari = new Follower("Andari");
        Follower wandi = new Follower("Wandi");
        Follower agung = new Follower("Agung");
        Follower rahmadi = new Follower("Dayat");
        Follower hafif = new Follower("Hafif");
        Follower hanif = new Follower("Hanif");

        ustKhalid.register(rahmadi);
        ustKhalid.register(hanif);
        ustKhalid.register(hafif);
        System.out.println("");
        ustFiranda.register(agung);
        ustFiranda.register(wandi);
        ustFiranda.register(rahmad);

        ustKhalid.tweet("Assalamualaikum temen-temen gimana kabarnya");
        ustFiranda.tweet("Khaifa halluk");

        ustKhalid.unregister(andari);

        ustKhalid.tweet("Barakallah fikum");
    }
}