Generate event when stack changed

Question

I have a task develop a class Stack that generate event when you add new element ? Develop a class Stack is not a problem, what means event that apears when a new element is added ?[                                                                                                                                                                                                                                                                                                                                                                                               

Answer 1

That about awt / swing ..or I can to apply listeners
to My Stack ?Sorry, I thought there were also non-GUI examples there. Apparently not.
It's probably the intention to implement the observer pattern into your code.
Here's a small demo of how this can be done:import java.util.List;
import java.util.ArrayList;
class Main {
    public static void main(String[] args) {
        MagazinePublisher publisher = new MagazinePublisher();
        Subscriber carl = new Subscriber("Carl");
        Subscriber pete = new Subscriber("Pete");
        Subscriber zeke = new Subscriber("Zeke");
        publisher.registerObservers(carl);
        publisher.registerObservers(pete);
        // whenever the state of the 'publisher' changes, it's
        // subscribers should be notified
        publisher.notifyObservers();
        publisher.registerObservers(zeke);
        publisher.notifyObservers();
        publisher.removeObservers(pete);
        publisher.removeObservers(carl);
        publisher.notifyObservers();
interface MyObserver {
    void update(int edition);
interface MySubject {
    void registerObservers(MyObserver mo);
    void removeObservers(MyObserver mo);
    void notifyObservers();
class MagazinePublisher implements MySubject {
    List<MyObserver> observers;
    int edition;
    public MagazinePublisher() {
        observers = new ArrayList<MyObserver>();
        edition = 1;
    public void notifyObservers() {
        for(MyObserver mo : observers) {
            mo.update(edition);
        edition++;
    public void registerObservers(MyObserver mo) {
        observers.add(mo);
    public void removeObservers(MyObserver mo) {
        observers.remove(mo);
class Subscriber implements MyObserver {
    String name;
    public Subscriber(String n) {
        name = n;
    public boolean equals(Object o) {
        return this.name.equals(((Subscriber)o).name);
    public void update(int e) {
        System.out.println(name+" recieved a copy of the "+e+" edition!");
    // hashCode() and other methods ...
}Details about this design pattern:
http://en.wikipedia.org/wiki/Observer_pattern
or Google, of course:
http://www.google.com/search?hl=en&q=Observer+pattern&btnG=Google+Search
Good luck!