javax.swing.undo
Class UndoManager

java.lang.Object
  javax.swing.undo.AbstractUndoableEdit
      javax.swing.undo.CompoundEdit
          javax.swing.undo.UndoManager

All Implemented Interfaces:

Serializable, EventListener, UndoableEditListener, UndoableEdit

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 JavaBeans^TM 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 - if canUndo returns false

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

Returns:

true if this edit is alive and hasBeenDone is true

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 - if canRedo returns false

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

Returns:

true if this edit is alive and hasBeenDone is false

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

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:

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

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:

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