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, DefaultStyledDocument.StyleChangeUndoableEdit, GapContent.InsertUndo, GapContent.RemoveUndo, StateEdit, StringContent.InsertUndo, StringContent.RemoveUndo

public class AbstractUndoableEdit

extends Object

implements UndoableEdit, Serializable

An abstract implementation of UndoableEdit, implementing simple responses to all boolean methods in that interface.

Author:

Ray Ryan

See Also:

Serialized Form

Field Summary

(package private) boolean	alive True if this edit has not received die; defaults to true.
(package private) boolean	hasBeenDone Defaults to true; becomes false if this edit is undone, true again if it is redone.
protected static String	RedoName String returned by getRedoPresentationName; as of Java 2 platform v1.3.1 this field is no longer used.
protected static String	UndoName String returned by getUndoPresentationName; as of Java 2 platform v1.3.1 this field is no longer used.

Constructor Summary

AbstractUndoableEdit()
Creates an AbstractUndoableEdit which defaults and alive to true.

Method Summary

boolean	addEdit(UndoableEdit anEdit) This default implementation returns false.
boolean	canRedo() Returns true if this edit is alive and hasBeenDone is false.
boolean	canUndo() Returns true if this edit is alive and hasBeenDone is true.
void	die() Sets alive to false.
String	getPresentationName() This default implementation returns "".
String	getRedoPresentationName() Retreives the value from the defaults table with key AbstractUndoableEdit.redoText and returns that value followed by a space, followed by getPresentationName.
String	getUndoPresentationName() Retreives the value from the defaults table with key AbstractUndoableEdit.undoText and returns that value followed by a space, followed by getPresentationName.
boolean	isSignificant() This default implementation returns true.
void	redo() Throws CannotRedoException if canRedo returns false.
boolean	replaceEdit(UndoableEdit anEdit) This default implementation returns false.
String	toString() Returns a string that displays and identifies this object's properties.
void	undo() Throws CannotUndoException if canUndo returns false.

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

String returned by getUndoPresentationName; as of Java 2 platform v1.3.1 this field is no longer used. This value is now localized and comes from the defaults table with key AbstractUndoableEdit.undoText.

See Also:

UIDefaults, Constant Field Values

RedoName

protected static final String RedoName

String returned by getRedoPresentationName; as of Java 2 platform v1.3.1 this field is no longer used. This value is now localized and comes from the defaults table with key AbstractUndoableEdit.redoText.

See Also:

UIDefaults, Constant Field Values

hasBeenDone

boolean hasBeenDone

Defaults to true; becomes false if this edit is undone, true again if it is redone.

alive

boolean alive

True if this edit has not received die; defaults to true.

Constructor Detail

AbstractUndoableEdit

public AbstractUndoableEdit()

Creates an AbstractUndoableEdit which defaults and alive to true.

Method Detail

die

public void die()

Sets alive to false. Note that this is a one way operation; dead edits cannot be resurrected. Sending undo or redo to a dead edit results in an exception being thrown.

Typically an edit is killed when it is consolidated by another edit's addEdit or replaceEdit method, or when it is dequeued from an UndoManager.

Specified by:

die in interface UndoableEdit

See Also:

CompoundEdit.die()

undo

public void undo()
          throws CannotUndoException

Throws CannotUndoException if canUndo returns false. Sets hasBeenDone to false. Subclasses should override to undo the operation represented by this edit. Override should begin with a call to super.

Specified by:

undo in interface UndoableEdit

Throws:

CannotUndoException - if canUndo returns false

See Also:

canUndo()

canUndo

public boolean canUndo()

Returns true if this edit is alive and hasBeenDone is true.

Specified by:

canUndo in interface UndoableEdit

Returns:

true if this edit is alive and hasBeenDone is true

See Also:

die(), undo(), redo()

redo

public void redo()
          throws CannotRedoException

Throws CannotRedoException if canRedo returns false. Sets hasBeenDone to true. Subclasses should override to redo the operation represented by this edit. Override should begin with a call to super.

Specified by:

redo in interface UndoableEdit

Throws:

CannotRedoException - if canRedo returns false

See Also:

canRedo()

canRedo

public boolean canRedo()

Returns true if this edit is alive and hasBeenDone is false.

Specified by:

canRedo in interface UndoableEdit

Returns:

true if this edit is alive and hasBeenDone is false

See Also:

die(), undo(), redo()

addEdit

public boolean addEdit(UndoableEdit anEdit)

This default implementation returns false.

Specified by:

addEdit in interface UndoableEdit

Parameters:

anEdit - the edit to be added

Returns:

false

See Also:

UndoableEdit.addEdit(javax.swing.undo.UndoableEdit)

replaceEdit

public boolean replaceEdit(UndoableEdit anEdit)

This default implementation returns false.

Specified by:

replaceEdit in interface UndoableEdit

Parameters:

anEdit - the edit to replace

Returns:

false

See Also:

UndoableEdit.replaceEdit(javax.swing.undo.UndoableEdit)

isSignificant

public boolean isSignificant()

This default implementation returns true.

Specified by:

isSignificant in interface UndoableEdit

Returns:

true

See Also:

UndoableEdit.isSignificant()

getPresentationName

public String getPresentationName()

This default implementation returns "". Used by getUndoPresentationName and getRedoPresentationName to construct the strings they return. Subclasses should override to return an appropriate description of the operation this edit represents.

Specified by:

getPresentationName in interface UndoableEdit

Returns:

the empty string ""

See Also:

getUndoPresentationName(), getRedoPresentationName()

getUndoPresentationName

public String getUndoPresentationName()

Retreives the value from the defaults table with key AbstractUndoableEdit.undoText and returns that value followed by a space, followed by getPresentationName. If getPresentationName returns "", then the defaults value is returned alone.

Specified by:

getUndoPresentationName in interface UndoableEdit

Returns:

the value from the defaults table with key AbstractUndoableEdit.undoText, followed by a space, followed by getPresentationName unless getPresentationName is "" in which case, the defaults value is returned alone.

See Also:

getPresentationName()

getRedoPresentationName

public String getRedoPresentationName()

Retreives the value from the defaults table with key AbstractUndoableEdit.redoText and returns that value followed by a space, followed by getPresentationName. If getPresentationName returns "", then the defaults value is returned alone.

Specified by:

getRedoPresentationName in interface UndoableEdit

Returns:

the value from the defaults table with key AbstractUndoableEdit.redoText, followed by a space, followed by getPresentationName unless getPresentationName is "" in which case, the defaults value is returned alone.

See Also:

getPresentationName()

toString

public String toString()

Returns a string that displays and identifies this object's properties.

Overrides:

toString in class Object

Returns:

a String representation of this object