Class ListEventAssembler<E>


  • public final class ListEventAssembler<E>
    extends java.lang.Object
    Models a continuous stream of changes on a list. Changes of the same type that occur on a continuous set of rows are grouped into blocks automatically for performance benefits.

    Atomic sets of changes may involve many lines of changes and many blocks of changes. They are committed to the queue in one action. No other threads should be creating a change on the same list change queue when an atomic change is being created.

    Author:
    Jesse Wilson
    • Field Detail

      • sourceList

        protected EventList<E> sourceList
        the list that this tracks changes for
      • eventLevel

        protected int eventLevel
        the event level is the number of nested events
      • allowNestedEvents

        protected boolean allowNestedEvents
        whether to allow nested events
      • reorderMap

        protected int[] reorderMap
        the current reordering array if this change is a reorder
    • Constructor Detail

      • ListEventAssembler

        public ListEventAssembler​(EventList<E> sourceList,
                                  ListEventPublisher publisher)
        Creates a new ListEventAssembler that tracks changes for the specified list.
    • Method Detail

      • beginEvent

        public void beginEvent()
        Starts a new atomic change to this list change queue.

        This simple change event does not support change events nested within. To allow other methods to nest change events within a change event, use beginEvent(true).

      • beginEvent

        public void beginEvent​(boolean allowNestedEvents)
        Starts a new atomic change to this list change queue. This signature allows you to specify allowing nested changes. This simply means that you can call other methods that contain a beginEvent(), commitEvent() block and their changes will be recorded but not fired. This allows the creation of list modification methods to call simpler list modification methods while still firing a single ListEvent to listeners.
        Parameters:
        allowNestedEvents - false to throw an exception if another call to beginEvent() is made before the next call to commitEvent(). Nested events allow multiple method's events to be composed into a single event.
        See Also:
        Bug 52
      • elementInserted

        public void elementInserted​(int index,
                                    E newValue)
        Add to the current ListEvent the insert of the element at the specified index, with the specified previous value.
      • elementUpdated

        public void elementUpdated​(int index,
                                   E oldValue,
                                   E newValue)
        Add to the current ListEvent the update of the element at the specified index, with the specified previous value.
      • elementDeleted

        public void elementDeleted​(int index,
                                   E oldValue)
        Add to the current ListEvent the removal of the element at the specified index, with the specified previous value.
      • addChange

        public void addChange​(int type,
                              int startIndex,
                              int endIndex)
        Adds a block of changes to the set of list changes. The change block allows a range of changes to be grouped together for efficiency.

        One or more calls to this method must be prefixed by a call to beginEvent() and followed by a call to commitEvent().

      • addInsert

        public void addInsert​(int index)
        Deprecated.
        Convenience method for appending a single insert.
      • addDelete

        public void addDelete​(int index)
        Deprecated.
        replaced with elementDeleted(int, E).
        Convenience method for appending a single delete.
      • addUpdate

        public void addUpdate​(int index)
        Deprecated.
        Convenience method for appending a single update.
      • addInsert

        public void addInsert​(int startIndex,
                              int endIndex)
        Deprecated.
        Convenience method for appending a range of inserts.
      • addDelete

        public void addDelete​(int startIndex,
                              int endIndex)
        Deprecated.
        replaced with elementDeleted(int, E).
        Convenience method for appending a range of deletes.
      • addUpdate

        public void addUpdate​(int startIndex,
                              int endIndex)
        Deprecated.
        Convenience method for appending a range of updates.
      • reorder

        public void reorder​(int[] reorderMap)
        Sets the current event as a reordering. Reordering events cannot be combined with other events.
      • forwardEvent

        public void forwardEvent​(ListEvent<?> listChanges)
        Forwards the event. This is a convenience method that does the following:
        1. beginEvent()
        2. For all changes in sourceEvent, apply those changes to this
        3. commitEvent()

        Note that this method should be preferred to manually forwarding events because it is heavily optimized.

        Note that currently this implementation does a best effort to preserve reorderings. This means that a reordering is lost if it is combined with any other ListEvent.

      • commitEvent

        public void commitEvent()
        Commits the current atomic change to this list change queue. This will notify all listeners about the change.

        If the current event is nested within a greater event, this will simply change the nesting level so that further changes are applied directly to the parent change.

      • discardEvent

        public void discardEvent()
        Discards the current atomic change to this list change queue. This does not notify any listeners about any changes.

        The caller of this method is responsible for returning the EventList to its state before the event began. If they fail to do so, the EventList pipeline may be in an inconsistent state.

        If the current event is nested within a greater event, this will discard changes at the current nesting level and that further changes are still applied directly to the parent change.

      • isEventEmpty

        public boolean isEventEmpty()
        Returns true if the current atomic change to this list change queue is empty; false otherwise.
        Returns:
        true if the current atomic change to this list change queue is empty; false otherwise
      • addListEventListener

        public void addListEventListener​(ListEventListener<? super E> listChangeListener)
        Registers the specified listener to be notified whenever new changes are appended to this list change sequence.

        For each listener, a ListEvent is created, which provides a read-only view to the list changes in the list. The same ListChangeView object is used for all notifications to the specified listener, so if a listener does not process a set of changes, those changes will persist in the next notification.

        Parameters:
        listChangeListener - event listener != null
        Throws:
        java.lang.NullPointerException - if the specified listener is null
      • removeListEventListener

        public void removeListEventListener​(ListEventListener<? super E> listChangeListener)
        Removes the specified listener from receiving notification when new changes are appended to this list change sequence.

        This uses the == identity comparison to find the listener instead of equals(). This is because multiple Lists may be listening and therefore equals() may be ambiguous.

        Parameters:
        listChangeListener - event listener != null
        Throws:
        java.lang.NullPointerException - if the specified listener is null
        java.lang.IllegalArgumentException - if the specified listener wasn't added before