/**
  * Copyright (c): Uwe Schmidt, FH Wedel
  *
  * You may study, modify and distribute this source code
  * FOR NON-COMMERCIAL PURPOSES ONLY.
  * This copyright message has to remain unchanged.
  *
  * Note that this document is provided 'as is',
  * WITHOUT WARRANTY of any kind either expressed or implied.
  */

/* das Modell:
 * die Counter Klasse mit
 * den Routinen zur Ereignis-Verwaltung
 */

import java.util.Vector;

public
class Counter {
  int cnt;

  public
  Counter() {
    this.cnt = 0;
    counterChangedListeners = new Vector();
  }

  //--------------------

  public
  void incr(int i) {
    cnt += i;

    notifyCounterChanged();
  }

  //--------------------
  // event listener verwalten

  private
  Vector counterChangedListeners;

  protected
  void notifyCounterChanged() {
    Vector l;
    CounterChangedEvent e = new CounterChangedEvent(this,cnt);

    synchronized (this) {
      l = (Vector)counterChangedListeners.clone();
    }

    for ( int i = 0;
	  i < l.size();
	  ++i ) {
      ((CounterChangedListener)l.elementAt(i)).counterChanged(e);
    }
  }

  //--------------------

  public
  synchronized
  void addCounterChangedListener(CounterChangedListener l) {
    counterChangedListeners.addElement(l);
  }

  public
  synchronized
  void removeCounterChangedListener(CounterChangedListener l) {
    counterChangedListeners.removeElement(l);
  }
}