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.
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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.