Package javafx.beans
The package javafx.beans contains the interfaces that
                define the most generic form of observability. All other classes in
                the JavaFX library, that are observable, extend the Observable
                interface.
An implementation of Observable allows to attach an
                InvalidationListener. The contentBinding gets notified every time
                the Observable may have changed. Typical implementations of
                Observable are all properties, all bindings, ObservableList, and ObservableMap.
An InvalidationListener will get no further information,
                e.g. it will not get the old and the new value of a property. If you
                need more information consider using a ChangeListener for properties and bindings, ListChangeListener for ObservableLists or
                MapChangeListener for ObservableMap
                instead.
- 
ClassDescriptionSpecifies a property to which child elements will be added or set when an explicit property is not given.AnInvalidationListeneris notified whenever anObservablebecomes invalid.Annotation that provides information about argument's name.AnObservableis an entity that wraps content and allows to observe the content for invalidations.AWeakInvalidationListenercan be used if anObservableshould only maintain a weak reference to the listener.WeakListeneris the super interface of all weak listener implementations in the JavaFX API.