question: public void registerPlotterListener ( PlotterChangedListener listener ) { plotterListeners . add ( listener ) ; if ( plotter != null ) { listener . plotterChanged ( plotter . getPlotterName ( ) ) ; } settingsListeners . addAll ( listener . getListeningObjects ( ) ) ; for ( PlotterSettingsChangedListener settingsListener : listener . getListeningObjects ( ) ) { informSettingsListener ( settingsListener ) ; } }
target:  This listener will be registered and immediately informed about the current plotter