Module javafx.base
Package javafx.beans

Class WeakInvalidationListener

  • All Implemented Interfaces:
    InvalidationListener, WeakListener

    public final class WeakInvalidationListener
extends Object
implements InvalidationListener, WeakListener
    A WeakInvalidationListener can be used, if an Observable should only maintain a weak reference to the listener. This helps to avoid memory leaks, that can occur if observers are not unregistered from observed objects after use.

    WeakInvalidationListener are created by passing in the original InvalidationListener. The WeakInvalidationListener should then be registered to listen for changes of the observed object.

    Note: You have to keep a reference to the InvalidationListener, that was passed in as long as it is in use, otherwise it will be garbage collected to soon.

    Since:
    JavaFX 2.0
    See Also:
    InvalidationListener, Observable

    • Constructor Detail

      • WeakInvalidationListener

        public WeakInvalidationListener​(InvalidationListener listener)
        The constructor of WeakInvalidationListener.
        Parameters:
        listener - The original listener that should be notified

    • Method Detail

      • wasGarbageCollected

        public boolean wasGarbageCollected​()
        Returns true if the linked listener was garbage-collected. In this case, the listener can be removed from the observable.
        Specified by:
        wasGarbageCollected in interface WeakListener
        Returns:
        true if the linked listener was garbage-collected.

      • invalidated

        public void invalidated​(Observable observable)
        This method needs to be provided by an implementation of InvalidationListener. It is called if an Observable becomes invalid.

        In general is is considered bad practice to modify the observed value in this method.

        Specified by:
        invalidated in interface InvalidationListener
        Parameters:
        observable - The Observable that became invalid