Java™ Platform
Standard Ed. 6

javax.swing.undo
Class StateEdit

java.lang.Object
  extended by javax.swing.undo.AbstractUndoableEdit
      extended by 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

Field Summary
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
           
protected  String undoRedoName
          The undo/redo presentation name
 
Fields inherited from class javax.swing.undo.AbstractUndoableEdit
RedoName, UndoName
 
Constructor Summary
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
 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)
           
 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
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)

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.


Java™ Platform
Standard Ed. 6

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