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Subject.java

class Subject 
{
     protected boolean changed;
     protected Vector obs;
     
     public Subject()
     {
          this.changed = false;
          this.obs = new Vector();
     }
     
     public synchronized void addObserver (Watcher o)
     {
          if (!this.obs.contains(o))
          {
               this.obs.addElement(o);
          }
     }
     
     public synchronized void deleteObserver (Watcher o)
     {
          this.obs.removeElement(o);
     }
     
     public void changeState ()
     {
          this.setChanged();
          this.notifyObservers();
     }
     
     protected synchronized void setChanged ()
     {
          this.changed = true;
     }
     
     public void notifyObservers ()
     {
          this.notifyObservers(null);
     }
     
     protected synchronized void clearChanged ()
     {
          this.changed = false;
     }
     
     public synchronized int countObservers ()
     {
          return this.obs.size();
     }
     
     public synchronized void deleteObservers ()
     {
          this.obs.removeAllElements();
     }
     
     public synchronized boolean hasChanged ()
     {
          return this.changed;
     }
     
     public void notifyObservers (java.lang.Object arg)
     {
          java.lang.Object[] arrLocal;
          synchronized (this)
          {
               if (!this.changed)
               {
                    return;
               }
               arrLocal = this.obs.toArray();
               this.changed = false;
          }
          if (this.obs.size() != arrLocal.length)
          {
          }
          for (int i = (arrLocal.length - 1); i >= 0; i = (i - 1))
          {
               ((Watcher) arrLocal[i]).update(this,arg);
          }
     }
}

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