javax.swing.undo

Class AbstractUndoableEdit

java.lang.Object

javax.swing.undo.AbstractUndoableEdit

All Implemented Interfaces:

Serializable, UndoableEdit

Direct Known 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

Fields

Modifier and Type	Field and Description
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

Constructors

Constructor and Description
AbstractUndoableEdit() Constructs a new AbstractUndoableEdit.

Method Summary

Methods

Modifier and Type	Method and Description
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, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

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”.

See Also:

Constant Field Values

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”.

See Also:

Constant Field Values

Constructor Detail

AbstractUndoableEdit

public AbstractUndoableEdit()

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

Method Detail

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()

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()

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()

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()

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

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.

Returns:

true if the edit was combined successfully, and false if it could not be combined.

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.

Returns:

true if the edit is successfully replaced, and false otherwise.

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.

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

Returns:

The presentation name.

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

Returns:

The undo presentation name.

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

Returns:

The redo presentation name.

toString

public String toString()

Description copied from class: Object

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 class Object

Returns:

the String representing this Object, which may be null

See Also:

Object.getClass(), Object.hashCode(), Class.getName(), Integer.toHexString(int)