public void addListener(RunListener listener) {
        if (listener == null) {
            throw new NullPointerException("Cannot add a null listener");
        }
        listeners.add(wrapIfNotThreadSafe(listener));
    }
public void addListener ( RunListener listener ) { if ( listener == null ) { throw new NullPointerException ( "Cannot add a null listener" ) ; } listeners . add ( wrapIfNotThreadSafe ( listener ) ) ; }
Internal use only