Signals that an AWT component, JavaBeans component, or Swing component can have only one EventListener object registered for some specific type of event. That is, it signals that a particular event is a unicast event rather than a multicast event. This exception type serves a formal purpose in the Java event model; its presence in the throws clause of an EventListener registration method (even if the method never actually throws the exception) signals that an event is a unicast event.

Figure 16-62. java.util.TooManyListenersException

public class TooManyListenersException extends Exception {
// Public Constructors
     public TooManyListenersException( );  
     public TooManyListenersException(String s);  
}