public class ThisEscape { 
... 
 public ThisEscape(EventSource source) { 
     source.registerListener(new EventListener() { 
                   public void onEvent(Event e) { 
                        doSomething(e); 
               } 
           }); 
 ... 
 } 
} 

public class SafeListener { 
     private final EventListener listener; 
     private SafeListener() { 
         listener = new EventListener() { 
                 public void onEvent(Event e) { 
                doSomething(e); 
          } 
         }; 
  } 

 public static SafeListener newInstance(EventSource source) { 
   SafeListener safe = new SafeListener(); 
   source.registerListener(safe.listener); 
 return safe; 
 } 
}