Module java.desktop

Package javax.swing.undo

Class StateEdit

java.lang.Object

javax.swing.undo.AbstractUndoableEdit

javax.swing.undo.StateEdit

All Implemented Interfaces:

Serializable, UndoableEdit

public class StateEdit
extends AbstractUndoableEdit

StateEdit is a general edit for objects that change state. Objects being edited must conform to the StateEditable interface.

This edit class works by asking an object to store it's state in Hashtables before and after editing occurs. Upon undo or redo the object is told to restore it's state from these Hashtables.

A state edit is used as follows:

      // Create the edit during the "before" state of the object
      StateEdit newEdit = new StateEdit(myObject);
      // Modify the object
      myObject.someStateModifyingMethod();
      // "end" the edit when you are done modifying the object
      newEdit.end();
 

Note that when a StateEdit ends, it removes redundant state from the Hashtables - A state Hashtable is not guaranteed to contain all keys/values placed into it when the state is stored!

See Also:

StateEditable, Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected StateEditable	object	The object being edited
protected Hashtable<Object,Object>	postState	The state information after the edit
protected Hashtable<Object,Object>	preState	The state information prior to the edit
protected static String	RCSID	Obsolete RCS version identity.
protected String	undoRedoName	The undo/redo presentation name

Fields inherited from class javax.swing.undo.AbstractUndoableEdit

RedoName, UndoName

Constructor Summary

Constructors

Constructor	Description
StateEdit(StateEditable anObject)	Create and return a new StateEdit.
StateEdit(StateEditable anObject, String name)	Create and return a new StateEdit with a presentation name.

Method Summary

Modifier and Type	Method	Description
void	end()	Gets the post-edit state of the StateEditable object and ends the edit.
String	getPresentationName()	Gets the presentation name for this edit
protected void	init(StateEditable anObject, String name)	Initialize the state edit.
void	redo()	Tells the edited object to apply the state after the edit
protected void	removeRedundantState()	Remove redundant key/values in state hashtables.
void	undo()	Tells the edited object to apply the state prior to the edit

Methods inherited from class javax.swing.undo.AbstractUndoableEdit

addEdit, canRedo, canUndo, die, getRedoPresentationName, getUndoPresentationName, isSignificant, replaceEdit, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

RCSID

protected static final String RCSID

Obsolete RCS version identity.

See Also:

Constant Field Values

object

protected StateEditable object

The object being edited

preState

protected Hashtable<Object,Object> preState

The state information prior to the edit

postState

protected Hashtable<Object,Object> postState

The state information after the edit

undoRedoName

protected String undoRedoName

The undo/redo presentation name

Constructor Detail

StateEdit

public StateEdit(StateEditable anObject)

Create and return a new StateEdit.

Parameters:

anObject - The object to watch for changing state

See Also:

StateEdit

StateEdit

public StateEdit(StateEditable anObject,
                 String name)

Create and return a new StateEdit with a presentation name.

Parameters:

anObject - The object to watch for changing state

name - The presentation name to be used for this edit

See Also:

StateEdit

Method Detail

init

protected void init(StateEditable anObject,
                    String name)

Initialize the state edit.

Parameters:

anObject - The object to watch for changing state

name - The presentation name to be used for this edit

end

public void end()

Gets the post-edit state of the StateEditable object and ends the edit.

undo

public void undo()

Tells the edited object to apply the state prior to the edit

Specified by:

undo in interface UndoableEdit

Overrides:

undo in class AbstractUndoableEdit

See Also:

AbstractUndoableEdit.canUndo()

redo

public void redo()

Tells the edited object to apply the state after the edit

Specified by:

redo in interface UndoableEdit

Overrides:

redo in class AbstractUndoableEdit

See Also:

AbstractUndoableEdit.canRedo()

getPresentationName

public String getPresentationName()

Gets the presentation name for this edit

Specified by:

getPresentationName in interface UndoableEdit

Overrides:

getPresentationName in class AbstractUndoableEdit

Returns:

the empty string ""

See Also:

AbstractUndoableEdit.getUndoPresentationName(), AbstractUndoableEdit.getRedoPresentationName()

removeRedundantState

protected void removeRedundantState()

Remove redundant key/values in state hashtables.