javax.swing.undo
Interface UndoableEdit

All Known Implementing Classes:

AbstractUndoableEdit

public interface UndoableEdit

An object representing an edit that has been done, and that can be undone and redone.

Author:

Ray Ryan

Method Summary

boolean	addEdit(UndoableEdit anEdit) This UndoableEdit should absorb anEdit if it can.
boolean	canRedo() True if it is still possible to redo this operation.
boolean	canUndo() True if it is still possible to undo this operation.
void	die() May be sent to inform an edit that it should no longer be used.
String	getPresentationName() Provides a localized, human readable description of this edit suitable for use in, say, a change log.
String	getRedoPresentationName() Provides a localized, human readable description of the redoable form of this edit, e.g. for use as a Redo menu item.
String	getUndoPresentationName() Provides a localized, human readable description of the undoable form of this edit, e.g. for use as an Undo menu item.
boolean	isSignificant() Returns false if this edit is insignificant--for example one that maintains the user's selection, but does not change any model state.
void	redo() Re-apply the edit, assuming that it has been undone.
boolean	replaceEdit(UndoableEdit anEdit) Returns true if this UndoableEdit should replace anEdit.
void	undo() Undo the edit that was made.

Method Detail

undo

public void undo()
          throws CannotUndoException

Undo the edit that was made.

Throws:

CannotUndoException

canUndo

public boolean canUndo()

True if it is still possible to undo this operation.

redo

public void redo()
          throws CannotRedoException

Re-apply the edit, assuming that it has been undone.

Throws:

CannotRedoException

canRedo

public boolean canRedo()

True if it is still possible to redo this operation.

die

public void die()

May be sent to inform an edit that it should no longer be used. 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()

addEdit

public boolean addEdit(UndoableEdit anEdit)

This UndoableEdit should absorb anEdit if it can. Returns true if has been incorporated, false if it has not.

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

replaceEdit

public boolean replaceEdit(UndoableEdit anEdit)

Returns true if this UndoableEdit should replace anEdit. The receiver should incorporate anEdit's state before returning true.

This message is the opposite of addEdit--anEdit has typically already been queued in a 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().

isSignificant

public boolean isSignificant()

Returns false if this edit is insignificant--for example one that maintains the user's selection, but does not change any model state. This status can be used by an UndoableEditListener (like UndoManager) when deciding which UndoableEdits to present to the user as Undo/Redo options, and which to perform as side effects of undoing or redoing other events.

getPresentationName

public String getPresentationName()

Provides a localized, human readable description of this edit suitable for use in, say, a change log.

getUndoPresentationName

public String getUndoPresentationName()

Provides a localized, human readable description of the undoable form of this edit, e.g. for use as an Undo menu item. Typically derived from getDescription.

getRedoPresentationName

public String getRedoPresentationName()

Provides a localized, human readable description of the redoable form of this edit, e.g. for use as a Redo menu item. Typically derived from getPresentationName.