| javax.swing.undo.UndoableEdit
All known Subclasses: javax.swing.undo.AbstractUndoableEdit,
| UndoableEdit | | public interface UndoableEdit (Code) | | An UndoableEdit represents an edit. The edit may
be undone, or if already undone the edit may be redone.
UndoableEdit is designed to be used with the
UndoManager. As UndoableEdits are generated
by an UndoableEditListener they are typically added to
the UndoManager. When an UndoableEdit
is added to an UndoManager the following occurs (assuming
end has not been called on the UndoManager):
- If the
UndoManager contains edits it will call
addEdit on the current edit passing in the new edit
as the argument. If addEdit returns true the
new edit is assumed to have been incorporated into the current edit and
the new edit will not be added to the list of current edits.
Edits can use addEdit as a way for smaller edits to
be incorporated into a larger edit and treated as a single edit.
- If
addEdit returns false replaceEdit
is called on the new edit with the current edit passed in as the
argument. This is the inverse of addEdit —
if the new edit returns true from replaceEdit, the new
edit replaces the current edit.
The UndoManager makes use of
isSignificant to determine how many edits should be
undone or redone. The UndoManager will undo or redo
all insignificant edits (isSignificant returns false)
between the current edit and the last or
next significant edit. addEdit and
replaceEdit can be used to treat multiple edits as
a single edit, returning false from isSignificant
allows for treating can be used to
have many smaller edits undone or redone at once. Similar functionality
can also be done using the addEdit method.
version:
1.27, 05/05/07
author:
Ray Ryan |
| Method Summary | |
| public boolean | addEdit(UndoableEdit anEdit)
Adds an UndoableEdit to this UndoableEdit.
This method can be used to coalesce smaller edits into a larger
compound edit. | | public boolean | canRedo()
Returns true if this edit may be redone. | | public boolean | canUndo()
Returns true if this edit may be undone. | | public void | die()
Informs the edit that it should no longer be used. | | public String | getPresentationName()
Returns a localized, human-readable description of this edit, suitable
for use in a change log, for example. | | public String | getRedoPresentationName()
Returns a localized, human-readable description of the redoable form of
this edit, suitable for use as a Redo menu item, for example. | | public String | getUndoPresentationName()
Returns a localized, human-readable description of the undoable form of
this edit, suitable for use as an Undo menu item, for example. | | public boolean | isSignificant()
Returns true if this edit is considered significant. | | public void | redo()
Re-applies the edit. | | public boolean | replaceEdit(UndoableEdit anEdit)
Returns true if this UndoableEdit should replace
anEdit. | | public void | undo()
Undo the edit. |
| addEdit | | public boolean addEdit(UndoableEdit anEdit)(Code) | | Adds an UndoableEdit to this UndoableEdit.
This method can be used to coalesce smaller edits into a larger
compound edit. For example, text editors typically allow
undo operations to apply to words or sentences. The text
editor may choose to generate edits on each key event, but allow
those edits to be coalesced into a more user-friendly unit, such as
a word. In this case, the UndoableEdit would
override addEdit to return true when the edits may
be coalesced.
A return value of true indicates anEdit was incorporated
into this edit. A return value of false indicates anEdit
may not be incorporated into this edit.
Typically the receiver is already in the queue of a
UndoManager (or other UndoableEditListener),
and is being given a chance to incorporate anEdit
rather than letting it be added to the queue in turn.
If true is returned, from now on anEdit must return
false from canUndo and canRedo,
and must throw the appropriate exception on undo or
redo.
Parameters:
anEdit - the edit to be added true if anEdit may be incorporated into thisedit |
| canRedo | | public boolean canRedo()(Code) | | Returns true if this edit may be redone.
true if this edit may be redone |
| canUndo | | public boolean canUndo()(Code) | | Returns true if this edit may be undone.
true if this edit may be undone |
| die | | public void die()(Code) | | Informs the edit that it should no longer be used. Once an
UndoableEdit has been marked as dead it can no longer
be undone or redone.
This is a useful hook for cleaning up state no longer
needed once undoing or redoing is impossible--for example,
deleting file resources used by objects that can no longer be
undeleted. UndoManager calls this before it dequeues edits.
Note that this is a one-way operation. There is no "un-die"
method.
See Also: CompoundEdit.die |
| getPresentationName | | public String getPresentationName()(Code) | | Returns a localized, human-readable description of this edit, suitable
for use in a change log, for example.
description of this edit |
| getRedoPresentationName | | public String getRedoPresentationName()(Code) | | Returns a localized, human-readable description of the redoable form of
this edit, suitable for use as a Redo menu item, for example. This is
typically derived from getPresentationName.
a description of the redoable form of this edit |
| getUndoPresentationName | | public String getUndoPresentationName()(Code) | | Returns a localized, human-readable description of the undoable form of
this edit, suitable for use as an Undo menu item, for example.
This is typically derived from getPresentationName.
a description of the undoable form of this edit |
| isSignificant | | public boolean isSignificant()(Code) | | Returns true if this edit is considered significant. A significant
edit is typically an edit that should be presented to the user, perhaps
on a menu item or tooltip. The UndoManager will undo,
or redo, all insignificant edits to the next significant edit.
true if this edit is significant |
| replaceEdit | | public boolean replaceEdit(UndoableEdit anEdit)(Code) | | Returns true if this UndoableEdit should replace
anEdit. This method is used by CompoundEdit
and the UndoManager; it is called if
anEdit could not be added to the current edit
(addEdit returns false).
This method provides a way for an edit to replace an existing edit.
This message is the opposite of addEdit--anEdit has typically
already been queued in an UndoManager (or other
UndoableEditListener), and the receiver is being given a chance
to take its place.
If true is returned, from now on anEdit must return false from
canUndo() and canRedo(), and must throw the appropriate
exception on undo() or redo().
Parameters:
anEdit - the edit that replaces the current edit true if this edit should replace anEdit |
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