UndoRedoSupport, as the name suggests, will provide generic support for
undoing and redoing groups of changes to an
EventList. The
granularity of each undoable edit is determined by the ListEvent from which
it was generated.
Not every change described in a ListEvent results in an undoable edit.
Specifically, a
mutation of a list element IN PLACE does
not produce an undoable edit. For example, an
ObservableElementList
which observes a change of an element, or a call to
List.set with
the same object at that index produce a ListEvent that does not have a
corresponding
UndoRedoSupport.Edit object. These ListEvents are ignored because they
lack sufficient information to undo or redo the change.
In general UndoRedoSupport only makes sense for use with a
BasicEventList or a trivial wrapper around a BasicEventList which
does not affect the order or type of the elements, such as an
ObservableElementList. Advanced transformations, such as
SortedList or
FilterList will not work as expected with this
UndoRedoSupport class since their contents are controlled by information
outside of themselves (
Comparators and
Matchers).
This class is agnostic to any particular GUI toolkit. As such it may be
used in a headless environment or can also be bound to a specific toolkit.