Abril 08
                               Prof(s). Ismael H. F. Santos & Eduardo Bezerra                                        31
Observer em Java
npublic class Observable extends Object {
n Collection<Observer> observers;
n public void addObserver(Observer o);
n public void deleteObserver(Observer o);
n  public boolean hasChanged();
n public void notifyObservers();
n public void notifyObservers(Object arg);
n …
n}
n
npublic abstract interface Observer {
n public abstract void update(Observable o, Object arg);
n}
n
npublic class Subject extends Observable{
n public void setState(String filename);
n  public string getState();
n}