void function ( ) { notifyObservers ( null ) ; }
if haschanged returns true , calls the update method for every observer in the list of observers using null as the argument . afterwards , calls clearchanged . equivalent to calling notifyobservers null . concode_field_sep boolean changed concode_elem_sep List<Observer> observers concode_field_sep void deleteObservers concode_elem_sep void addObserver 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