Package org.jdesktop.beansbinding

Class PropertyHelper<S,​V>

  • Type Parameters:
    S - the type of source object that this Property operates on
    V - the type of value that this Property represents
    Direct Known Subclasses:
    BeanProperty, ELProperty
    public abstract class PropertyHelper<S,​V>
extends Property<S,​V>
    An abstract subclass of Property that helps with the management of PropertyStateListeners by implementing the methods for adding, removing, and getting listeners. PropertyHelper can be constructed to manage listeners for multiple source objects, or to ignore the source object argument when dealing with listeners and associate them directly with the PropertyHelper instance itself. This makes PropertyHelper useful as a base for both property types described in the documentation for Property.

    PropertyHelper also provides, by way of the protected methods listeningStarted(S) and listeningStopped(S) a hook for subclasses to know when it's time to start tracking changes to a particular source object.

    Author:
    Shannon Hickey

    • Constructor Summary

      Constructors 
      Constructor Description
      PropertyHelper()
      Create a PropertyHelper that manages listeners for multiple source objects.
      PropertyHelper​(boolean ignoresSource)
      Create a PropertyHelper, specifying whether it manages listeners for multiple source objects, or ignores the source object argument when dealing with listeners

    • Constructor Detail

      • PropertyHelper

        public PropertyHelper()
        Create a PropertyHelper that manages listeners for multiple source objects.

      • PropertyHelper

        public PropertyHelper​(boolean ignoresSource)
        Create a PropertyHelper, specifying whether it manages listeners for multiple source objects, or ignores the source object argument when dealing with listeners
        Parameters:
        ignoresSource - whether or not the source argument is ignored when dealing with listeners

    • Method Detail

      • getValue

        public abstract V getValue​(S source)
        Returns the value of this Property for the given source.
        Specified by:
        getValue in class Property<S,​V>
        Parameters:
        source - the source object on which to operate
        Returns:
        the value of this Property for the given source
        Throws:
        UnsupportedOperationException - if the Property is not readable for the given source
        See Also:
        Property.isReadable(S)

      • isReadable

        public abstract boolean isReadable​(S source)
        Returns whether or not the Property is readable for the given source.
        Specified by:
        isReadable in class Property<S,​V>
        Parameters:
        source - the source object on which to operate
        Returns:
        whether or not the Property is readable for the given source.
        Throws:
        UnsupportedOperationException
        See Also:
        Property.isWriteable(S)

      • isWriteable

        public abstract boolean isWriteable​(S source)
        Returns whether or not the Property is writeable for the given source.
        Specified by:
        isWriteable in class Property<S,​V>
        Parameters:
        source - the source object on which to operate
        Returns:
        whether or not the Property is writeable for the given source.
        Throws:
        UnsupportedOperationException
        See Also:
        Property.isReadable(S)

      • listeningStarted

        protected void listeningStarted​(S source)
        Called when this PropertyHelper changes from having no listeners installed for the given source object to having listeners installed for the given source object. This is the ideal time for subclasses to install any listeners needed to track change on the source object.
        See Also:
        listeningStopped(S)

      • listeningStopped

        protected void listeningStopped​(S source)
        Called when this PropertyHelper changes from having listeners installed for the given source object to having no listeners installed for the given source object. This is the ideal time for subclasses to remove any listeners that they've installed to track changes on the source object.
        See Also:
        listeningStopped(S)

      • addPropertyStateListener

        public final void addPropertyStateListener​(S source,
                                           PropertyStateListener listener)
        Adds a PropertyStateListener to be notified when the state of the Property changes with respect to the given source. Does nothing if the listener is null. If a listener is added more than once, notifications are sent to that listener once for every time that it has been added. The ordering of listener notification is unspecified.
        Specified by:
        addPropertyStateListener in class Property<S,​V>
        Parameters:
        source - the source object on which to operate
        listener - the listener to be notified

      • removePropertyStateListener

        public final void removePropertyStateListener​(S source,
                                              PropertyStateListener listener)
        Removes a PropertyStateListener for the given source. Does nothing if the listener is null or is not one of those registered for this source object. If the listener being removed was registered more than once, only one occurrence of the listener is removed from the list of listeners. The ordering of listener notification is unspecified.
        Specified by:
        removePropertyStateListener in class Property<S,​V>
        Parameters:
        source - the source object on which to operate
        listener - the listener to be removed
        See Also:
        Property.addPropertyStateListener(S, org.jdesktop.beansbinding.PropertyStateListener)

      • firePropertyStateChange

        protected final void firePropertyStateChange​(PropertyStateEvent pse)
        Notify listeners that the state of this property has changed, as characterized by the given PropertyStateEvent. If this PropertyHelper is managing listeners for multiple sources, only the listeners associated with the object returned by the PropertyStateEvent's getSourceObject() method are notified.
        Parameters:
        pse - the PropertyStateEvent characterizing the state change

      • isListening

        public final boolean isListening​(S source)
        Returns whether or not there are any PropertyStateListeners installed for the given source object.
        Parameters:
        source - the source object of interest
        Returns:
        whether or not there are any PropertyStateListeners installed for the given source object