JavaTM 2 Platform
Std. Ed. v1.4.2

javax.swing.undo
Class UndoManager

java.lang.Object
  extended byjavax.swing.undo.AbstractUndoableEdit
      extended byjavax.swing.undo.CompoundEdit
          extended byjavax.swing.undo.UndoManager
All Implemented Interfaces:
EventListener, Serializable, UndoableEdit, UndoableEditListener

public class UndoManager
extends CompoundEdit
implements UndoableEditListener

Concrete subclass of CompoundEdit which can serve as a UndoableEditListener, consolidating the UndoableEditEvents from a variety of sources, and undoing or redoing them one at a time. Unlike AbstractUndoableEdit and CompoundEdit, the public methods of this class are synchronized, and should be safe to call from multiple threads. This should make UndoManager a convenient marshall for sets of undoable JavaBeans.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeansTM has been added to the java.beans package. Please see XMLEncoder.


Field Summary
 
Fields inherited from class javax.swing.undo.CompoundEdit
edits
 
Fields inherited from class javax.swing.undo.AbstractUndoableEdit
RedoName, UndoName
 
Constructor Summary
UndoManager()
           
 
Method Summary
 boolean addEdit(UndoableEdit anEdit)
          If inProgress, inserts anEdit at indexOfNextAdd, and removes any old edits that were at indexOfNextAdd or later.
 boolean canRedo()
          Overridden to preserve usual semantics: returns true if a redo operation would be successful now, false otherwise
 boolean canUndo()
          Overridden to preserve usual semantics: returns true if an undo operation would be successful now, false otherwise
 boolean canUndoOrRedo()
          Return true if calling undoOrRedo will undo or redo.
 void discardAllEdits()
          Empty the undo manager, sending each edit a die message in the process.
protected  UndoableEdit editToBeRedone()
          Returns the the next significant edit to be redone if redo is called.
protected  UndoableEdit editToBeUndone()
          Returns the the next significant edit to be undone if undo is called.
 void end()
          Sending end() to an UndoManager turns it into a plain old (ended) CompoundEdit.
 int getLimit()
          Returns the maximum number of edits this UndoManager will hold.
 String getRedoPresentationName()
          If inProgress, returns getRedoPresentationName of the significant edit that will be redone when redo() is invoked.
 String getUndoOrRedoPresentationName()
          Return the appropriate name for a command that toggles between undo and redo.
 String getUndoPresentationName()
          If inProgress, returns getUndoPresentationName of the significant edit that will be undone when undo() is invoked.
 void redo()
          If this UndoManager is inProgress, redoes the last significant UndoableEdit at indexOfNextAdd or after, and all insignificant edits up to it.
protected  void redoTo(UndoableEdit edit)
          Redoes all changes from indexOfNextAdd to edit.
 void setLimit(int l)
          Set the maximum number of edits this UndoManager will hold.
 String toString()
          Returns a string that displays and identifies this object's properties.
protected  void trimEdits(int from, int to)
          Tell the edits in the given range (inclusive) to die, and remove them from edits.
protected  void trimForLimit()
          Reduce the number of queued edits to a range of size limit, centered on indexOfNextAdd.
 void undo()
          If this UndoManager is inProgress, undo the last significant UndoableEdit before indexOfNextAdd, and all insignificant edits back to it.
 void undoableEditHappened(UndoableEditEvent e)
          Called by the UndoabledEdit sources this UndoManager listens to.
 void undoOrRedo()
          Undo or redo as appropriate.
protected  void undoTo(UndoableEdit edit)
          Undoes all changes from indexOfNextAdd to edit.
 
Methods inherited from class javax.swing.undo.CompoundEdit
die, getPresentationName, isInProgress, isSignificant, lastEdit
 
Methods inherited from class javax.swing.undo.AbstractUndoableEdit
replaceEdit
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

UndoManager

public UndoManager()
Method Detail

getLimit

public int getLimit()
Returns the maximum number of edits this UndoManager will hold. Default value is 100.

See Also:
addEdit(javax.swing.undo.UndoableEdit), setLimit(int)

discardAllEdits

public void discardAllEdits()
Empty the undo manager, sending each edit a die message in the process.


trimForLimit

protected void trimForLimit()
Reduce the number of queued edits to a range of size limit, centered on indexOfNextAdd.


trimEdits

protected void trimEdits(int from,
                         int to)
Tell the edits in the given range (inclusive) to die, and remove them from edits. from > to is a no-op.


setLimit

public void setLimit(int l)
Set the maximum number of edits this UndoManager will hold. If edits need to be discarded to shrink the limit, they will be told to die in the reverse of the order that they were added.

See Also:
addEdit(javax.swing.undo.UndoableEdit), getLimit()

editToBeUndone

protected UndoableEdit editToBeUndone()
Returns the the next significant edit to be undone if undo is called. May return null


editToBeRedone

protected UndoableEdit editToBeRedone()
Returns the the next significant edit to be redone if redo is called. May return null


undoTo

protected void undoTo(UndoableEdit edit)
               throws CannotUndoException
Undoes all changes from indexOfNextAdd to edit. Updates indexOfNextAdd accordingly.

Throws:
CannotUndoException

redoTo

protected void redoTo(UndoableEdit edit)
               throws CannotRedoException
Redoes all changes from indexOfNextAdd to edit. Updates indexOfNextAdd accordingly.

Throws:
CannotRedoException

undoOrRedo

public void undoOrRedo()
                throws CannotRedoException,
                       CannotUndoException
Undo or redo as appropriate. Suitable for binding to an action that toggles between these two functions. Only makes sense to send this if limit == 1.

Throws:
CannotRedoException
CannotUndoException
See Also:
canUndoOrRedo(), getUndoOrRedoPresentationName()

canUndoOrRedo

public boolean canUndoOrRedo()
Return true if calling undoOrRedo will undo or redo. Suitable for deciding to enable a command that toggles between the two functions, which only makes sense to use if limit == 1.

See Also:
undoOrRedo()

undo

public void undo()
          throws CannotUndoException
If this UndoManager is inProgress, undo the last significant UndoableEdit before indexOfNextAdd, and all insignificant edits back to it. Updates indexOfNextAdd accordingly.

If not inProgress, indexOfNextAdd is ignored and super's routine is called.

Specified by:
undo in interface UndoableEdit
Overrides:
undo in class CompoundEdit
Throws:
CannotUndoException
See Also:
CompoundEdit.end()

canUndo

public boolean canUndo()
Overridden to preserve usual semantics: returns true if an undo operation would be successful now, false otherwise

Specified by:
canUndo in interface UndoableEdit
Overrides:
canUndo in class CompoundEdit
See Also:
CompoundEdit.isInProgress()

redo

public void redo()
          throws CannotRedoException
If this UndoManager is inProgress, redoes the last significant UndoableEdit at indexOfNextAdd or after, and all insignificant edits up to it. Updates indexOfNextAdd accordingly.

If not inProgress, indexOfNextAdd is ignored and super's routine is called.

Specified by:
redo in interface UndoableEdit
Overrides:
redo in class CompoundEdit
Throws:
CannotRedoException
See Also:
CompoundEdit.end()

canRedo

public boolean canRedo()
Overridden to preserve usual semantics: returns true if a redo operation would be successful now, false otherwise

Specified by:
canRedo in interface UndoableEdit
Overrides:
canRedo in class CompoundEdit
See Also:
CompoundEdit.isInProgress()

addEdit

public boolean addEdit(UndoableEdit anEdit)
If inProgress, inserts anEdit at indexOfNextAdd, and removes any old edits that were at indexOfNextAdd or later. The die method is called on each edit that is removed is sent, in the reverse of the order the edits were added. Updates indexOfNextAdd.

If not inProgress, acts as a CompoundEdit.

Specified by:
addEdit in interface UndoableEdit
Overrides:
addEdit in class CompoundEdit
Parameters:
anEdit - the edit to be added
Returns:
true if the edit is inProgress; otherwise returns false
See Also:
CompoundEdit.end(), CompoundEdit.addEdit(javax.swing.undo.UndoableEdit)

end

public void end()
Sending end() to an UndoManager turns it into a plain old (ended) CompoundEdit.

Calls super's end() method (making inProgress false), then sends die() to the unreachable edits at indexOfNextAdd and beyond, in the reverse of the order in which they were added.

Overrides:
end in class CompoundEdit
See Also:
CompoundEdit.end()

getUndoOrRedoPresentationName

public String getUndoOrRedoPresentationName()
Return the appropriate name for a command that toggles between undo and redo. Only makes sense to use such a command if limit == 1 and we're not in progress.


getUndoPresentationName

public String getUndoPresentationName()
If inProgress, returns getUndoPresentationName of the significant edit that will be undone when undo() is invoked. If there is none, returns AbstractUndoableEdit.undoText from the defaults table.

If not inProgress, acts as a CompoundEdit

Specified by:
getUndoPresentationName in interface UndoableEdit
Overrides:
getUndoPresentationName in class CompoundEdit
See Also:
undo(), CompoundEdit.getUndoPresentationName()

getRedoPresentationName

public String getRedoPresentationName()
If inProgress, returns getRedoPresentationName of the significant edit that will be redone when redo() is invoked. If there is none, returns AbstractUndoableEdit.redoText from the defaults table.

If not inProgress, acts as a CompoundEdit

Specified by:
getRedoPresentationName in interface UndoableEdit
Overrides:
getRedoPresentationName in class CompoundEdit
See Also:
redo(), CompoundEdit.getUndoPresentationName()

undoableEditHappened

public void undoableEditHappened(UndoableEditEvent e)
Called by the UndoabledEdit sources this UndoManager listens to. Calls addEdit with e.getEdit().

Specified by:
undoableEditHappened in interface UndoableEditListener
See Also:
addEdit(javax.swing.undo.UndoableEdit)

toString

public String toString()
Returns a string that displays and identifies this object's properties.

Overrides:
toString in class CompoundEdit
Returns:
a String representation of this object

JavaTM 2 Platform
Std. Ed. v1.4.2

Submit a bug or feature
For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

Copyright 2003 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.


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