adds an observer . if the observer was already added this method does nothing . concode_field_sep LinkedHashSet observers concode_elem_sep boolean changed concode_field_sep void deleteObservers concode_elem_sep boolean hasChanged concode_elem_sep void clearChanged concode_elem_sep int countObservers concode_elem_sep void deleteObserver concode_elem_sep void setChanged concode_elem_sep void notifyObservers concode_elem_sep void notifyObservers
void function ( Observer arg0 ) { if ( arg0 == null ) throw new NullPointerException ( "srini_string" ) ; observers . add ( arg0 ) ; }