Class ListenerList


  • public class ListenerList
    extends Object
    Internal class to maintain a list of listeners. This class is a thread-safe list that is optimized for frequent reads and infrequent writes. Copy on write is used to ensure readers can access the list without synchronization overhead. Readers are given access to the underlying array data structure for reading, with the trust that they will not modify the underlying array.

    Contains code from Eclipse org.eclipse.core.runtime.ListenerList class

    See Also:
    Eclipse.org
    • Field Detail

      • EQUALITY

        public static final int EQUALITY
        Mode constant (value 0) indicating that listeners should be compared using equality.
        See Also:
        Constant Field Values
      • IDENTITY

        public static final int IDENTITY
        Mode constant (value 1) indicating that listeners should be compared using identity.
        See Also:
        Constant Field Values
    • Constructor Detail

      • ListenerList

        public ListenerList()
        Creates a listener list.
      • ListenerList

        public ListenerList​(Comparator<?> comparator)
      • ListenerList

        public ListenerList​(int mode,
                            Comparator<?> comparator)
        Creates a listener list using the provided comparison mode.
    • Method Detail

      • add

        public void add​(Object listener)
        Adds the given listener to this list. Has no effect if an equal listener is already registered.

        This method is synchronized to protect against multiple threads adding or removing listeners concurrently. This does not block concurrent readers.

        Parameters:
        listener - the listener to add
      • getListeners

        public Object[] getListeners()
        Returns an array containing all the registered listeners. The resulting array is unaffected by subsequent adds or removes. If there are no listeners registered, the result is an empty array singleton instance (no garbage is created). Use this method when notifying listeners, so that any modifications to the listener list during the notification will have no effect on the notification itself.

        Note: callers must not modify the returned array.

        Returns:
        the list of registered listeners
      • getListenersCopy

        public Object[] getListenersCopy()
      • isEmpty

        public boolean isEmpty()
        Returns whether this listener list is empty.
        Returns:
        true if there are no registered listeners, and false otherwise
      • remove

        public void remove​(Object listener)
        Removes the given listener from this list. Has no effect if an identical listener was not already registered.

        This method is synchronized to protect against multiple threads adding or removing listeners concurrently. This does not block concurrent readers.

        Parameters:
        listener - the listener
      • size

        public int size()
        Returns the number of registered listeners.
        Returns:
        the number of registered listeners