public   class  Single {
	 private   static  Single instance;
	 private   boolean  state;

	 private  Single() {
		state = true;
	}

	 public  sinchronized  static  Single getInstance() {
		 if  (instance ==  null ) instance =  new  Single();
		 return  instance;
	}

	 public   void  setState( boolean  state) {
		 this .state = state;
	}

	 public   boolean  getState() {
		 return   this .state;
	}
}

 public   class  MyVerificator  implements  Runnable {
	 private   static  MyVerificator instance =  new  MyVerificator();
	 private  Set<MyListener> listeners =  new  HashSet<MyListener>();

	 private  MyVerificator() {
		 new  Thread( this ).start();
	}

	 public   static  MyVerificator getInstance() {
		 return  instance;
	}

	 public   void  run() {
		 try  {
			 while  (true) {
				 if  (![color=red]Single.getInstance().getState()[/color])
					dispatchUpdate();
			}
		}  catch  (Exception exception) {}
	}

	 public   void  addListener(MyListener listener) {
		 synchronized (listeners) {
			listeners.add(listener);
		}
	}

	 private   void  dispatchUpdate() {
		 synchronized (listeners) {
			 for  (MyListener listener : listeners) {
				listener.onChange();
			}
		}
	}
}