Lucida: An Analyzing Program Browser

class Subject { private List observers = new LinkedList(); void addObserver(Observer o) { observers.add(o); } protected void notifyObservers() { for (Iterator i = observers.iterator(); i.hasNext();) { ((Observer) i.next()).update(this); } } } class ConcreteSubject extends Subject { private final Date date = new Date(); void setDate(long milli) { date.setTime(milli); notifyObservers(); } Date getDate() {return date;} } interface Observer { void update(Subject s); } class ConcreteObserver implements Observer { private final ConcreteSubject s; ConcreteObserver(ConcreteSubject s) { this.s = s; s.addObserver(this); } void update(Subject s) { if (this.s == s) System.out.println(s.getDate()); } } Figure 3 Ownership contrasted with extraordinary uses for observer design pattern example