Module javafx.base

Interface ObservableValue<T>

    • Method Summary

      Modifier and Type Method Description
      void addListener​(ChangeListener<? super T> listener)
      Adds a ChangeListener which will be notified whenever the value of the ObservableValue changes.
      T getValue()
      Returns the current value of this ObservableValue
      void removeListener​(ChangeListener<? super T> listener)
      Removes the given listener from the list of listeners that are notified whenever the value of the ObservableValue changes.
    • Method Detail

      • addListener

        void addListener​(ChangeListener<? super T> listener)
        Adds a ChangeListener which will be notified whenever the value of the ObservableValue changes. If the same listener is added more than once, then it will be notified more than once. That is, no check is made to ensure uniqueness.

        Note that the same actual ChangeListener instance may be safely registered for different ObservableValues.

        The ObservableValue stores a strong reference to the listener which will prevent the listener from being garbage collected and may result in a memory leak. It is recommended to either unregister a listener by calling removeListener after use or to use an instance of WeakChangeListener avoid this situation.

        Parameters:
        listener - The listener to register
        Throws:
        NullPointerException - if the listener is null
        See Also:
        removeListener(ChangeListener)
      • removeListener

        void removeListener​(ChangeListener<? super T> listener)
        Removes the given listener from the list of listeners that are notified whenever the value of the ObservableValue changes.

        If the given listener has not been previously registered (i.e. it was never added) then this method call is a no-op. If it had been previously added then it will be removed. If it had been added more than once, then only the first occurrence will be removed.

        Parameters:
        listener - The listener to remove
        Throws:
        NullPointerException - if the listener is null
        See Also:
        addListener(ChangeListener)
      • getValue

        T getValue()
        Returns the current value of this ObservableValue
        Returns:
        The current value