Adding a [font=courier new]CollectionListener<Room>[/font] to home will inform you only on new and deleted rooms, as you noticed. If you want to listen to changes to the room points, you'll have to add a [font=courier new]PropertyChangeListener[/font] on each room (and remove it when the room is deleted), and update your text area when the property name in the event is equal to [font=courier new]Room.Property.POINTS.name()[/font].

[Please continue this thread in English because you started in English]