javax.swing.undo

Class AbstractUndoableEdit

Implemented Interfaces:
Serializable, UndoableEdit
Known Direct Subclasses:
AbstractDocument.ElementEdit, CompoundEdit, DefaultStyledDocument.AttributeUndoableEdit, StateEdit

public class AbstractUndoableEdit
extends Object
implements UndoableEdit, Serializable

A default implementation of UndoableEdit that can be used as a base for implementing editing operations.
See Also:
Serialized Form

Field Summary

protected static String
RedoName
The constant string “Redo”, which was returned by getRedoPresentationName() on early versions of the platform.
protected static String
UndoName
The constant string “Undo”, which was returned by getUndoPresentationName() on early versions of the platform.

Constructor Summary

AbstractUndoableEdit()
Constructs a new AbstractUndoableEdit.

Method Summary

boolean
addEdit(UndoableEdit edit)
Incorporates another editing action into this one, thus forming a combined action.
boolean
canRedo()
Determines whether it would be possible to redo this editing action.
boolean
canUndo()
Determines whether it would be possible to undo this editing action.
void
die()
Informs this edit action that it will no longer be used.
String
getPresentationName()
Returns a human-readable, localized name that describes this editing action and can be displayed to the user.
String
getRedoPresentationName()
Calculates a localized name for presenting the redo action to the user.
String
getUndoPresentationName()
Calculates a localized name for presenting the undo action to the user.
boolean
isSignificant()
Determines whether this editing action is significant enough for being seperately undoable by the user.
void
redo()
Redoes this editing action.
boolean
replaceEdit(UndoableEdit edit)
Incorporates another editing action into this one, thus forming a combined action that replaces the argument action.
String
toString()
Convert this Object to a human-readable String.
void
undo()
Undoes this editing action.

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

RedoName

protected static final String RedoName
The constant string “Redo”, which was returned by getRedoPresentationName() on early versions of the platform. However, this field has become obsolete with version 1.3.1. That method now retrieves a localized string from the UIManager, using the key “AbstractUndoableEdit.redoText”.
Field Value:
"Redo"

UndoName

protected static final String UndoName
The constant string “Undo”, which was returned by getUndoPresentationName() on early versions of the platform. However, this field has become obsolete with version 1.3.1. That method now retrieves a localized string from the UIManager, using the key “AbstractUndoableEdit.undoText”.
Field Value:
"Undo"

Constructor Details

AbstractUndoableEdit

public AbstractUndoableEdit()
Constructs a new AbstractUndoableEdit. The initial state is that the editing action is alive, and hasBeenDone is true.

Method Details

addEdit

public boolean addEdit(UndoableEdit edit)
Incorporates another editing action into this one, thus forming a combined action.

The default implementation always returns false, indicating that the editing action could not be incorporated.

Specified by:
addEdit in interface UndoableEdit
Parameters:
edit - the editing action to be incorporated.

canRedo

public boolean canRedo()
Determines whether it would be possible to redo this editing action.
Specified by:
canRedo in interface UndoableEdit
Returns:
true to indicate that this action can be redone, false otherwise.
See Also:
redo(), canUndo()

canUndo

public boolean canUndo()
Determines whether it would be possible to undo this editing action.
Specified by:
canUndo in interface UndoableEdit
Returns:
true to indicate that this action can be undone, false otherwise.
See Also:
undo(), canRedo()

die

public void die()
Informs this edit action that it will no longer be used. Some actions might use this information to release resources, for example open files. Called by UndoManager before this action is removed from the edit queue.
Specified by:
die in interface UndoableEdit

getPresentationName

public String getPresentationName()
Returns a human-readable, localized name that describes this editing action and can be displayed to the user.

The default implementation returns an empty string.

Specified by:
getPresentationName in interface UndoableEdit

getRedoPresentationName

public String getRedoPresentationName()
Calculates a localized name for presenting the redo action to the user.

The default implementation returns the concatenation of the string “Redo” and the action name, which is determined by calling getPresentationName().

The string “Redo” is retrieved from the UIManager, using the key “AbstractUndoableEdit.redoText”. This allows the text to be localized.

Specified by:
getRedoPresentationName in interface UndoableEdit

getUndoPresentationName

public String getUndoPresentationName()
Calculates a localized name for presenting the undo action to the user.

The default implementation returns the concatenation of the string “Undo” and the action name, which is determined by calling getPresentationName().

The string “Undo” is retrieved from the UIManager, using the key “AbstractUndoableEdit.undoText”. This allows the text to be localized.

Specified by:
getUndoPresentationName in interface UndoableEdit

isSignificant

public boolean isSignificant()
Determines whether this editing action is significant enough for being seperately undoable by the user. A typical significant action would be the resizing of an object. However, changing the selection in a text document would usually not be considered significant.

The default implementation returns true.

Specified by:
isSignificant in interface UndoableEdit
Returns:
true to indicate that the action is significant enough for being separately undoable, or false otherwise.

redo

public void redo()
            throws CannotRedoException
Redoes this editing action.
Specified by:
redo in interface UndoableEdit
Throws:
CannotRedoException - if canRedo() returns false, for example because this action has not yet been undone.
See Also:
canRedo(), undo()

replaceEdit

public boolean replaceEdit(UndoableEdit edit)
Incorporates another editing action into this one, thus forming a combined action that replaces the argument action.

The default implementation always returns false, indicating that the argument action should not be replaced.

Specified by:
replaceEdit in interface UndoableEdit
Parameters:
edit - the editing action to be replaced.

toString

public String toString()
Convert this Object to a human-readable String. There are no limits placed on how long this String should be or what it should contain. We suggest you make it as intuitive as possible to be able to place it into System.out.println() and such.

It is typical, but not required, to ensure that this method never completes abruptly with a RuntimeException.

This method will be called when performing string concatenation with this object. If the result is null, string concatenation will instead use "null".

The default implementation returns getClass().getName() + "@" + Integer.toHexString(hashCode()).

Overrides:
toString in interface Object
Returns:
the String representing this Object, which may be null

undo

public void undo()
            throws CannotUndoException
Undoes this editing action.
Specified by:
undo in interface UndoableEdit
Throws:
CannotUndoException - if canUndo() returns false, for example because this action has already been undone.
See Also:
canUndo(), redo()

AbstractUndoableEdit.java -- Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.