// ********** ObserverDemo.java **********
interface Observer { public void update(Observable o); }

class Observable {
  public static final int MAX_OBS = 500;
  private Observer[] observers = new Observer[MAX_OBS];
  private int num_observers = 0;
  public void addObserver(Observer o) {
    if (num_observers < MAX_OBS) observers[num_observers++] = o;
  }
  public void notifyObservers() {
    for (int i=0; i<num_observers; i++) observers[i].update(this); 
  }
}
class Observer1 implements Observer {
   public void update(Observable o) { int value = ((Observable1)o).getValue();  }
}
class Observable1 extends Observable {
  private int value = 0;
  public int getValue() { return value; }
  public void setValue(int newvalue) { value = newvalue; notifyObservers(); }
}
public class ObserverDemo {
  public static void main(String args[]) {
    long t1 = System.currentTimeMillis();
    Observer1[] observers = new Observer1[Observable.MAX_OBS];
    Observable1[] observables = new Observable1[Observable.MAX_OBS];
    for (int i=0; i<Observable.MAX_OBS; i++) 
      observers[i] = new Observer1();
    for (int j=0; j<Observable.MAX_OBS; j++) {
      observables[j] = new Observable1();
      for (int i=0; i<Observable.MAX_OBS; i++) 
        observables[j].addObserver(observers[i]);
    }
    for (int k=0; k<100; k++)  
      for (int j=0; j<Observable.MAX_OBS; j++) 
         observables[j].setValue(k); 

    long t2 = System.currentTimeMillis();
    System.out.print((t2-t1)+" ");
    System.out.flush();
  }
}