javax.swing.undo

Class UndoableEditSupport

public class UndoableEditSupport extends Object

A helper class for supporting {@link javax.swing.event.UndoableEditListener}.

Field Summary
protected CompoundEdit	compoundEdit compoundEdit
protected Vector<UndoableEditListener>	listeners The currently registered listeners.
protected Object	realSource The source of the broadcast UndoableEditEvents.
protected int	updateLevel The number of times that {@link #beginUpdate()} has been called without a matching call to {@link #endUpdate()}.

Constructor Summary
	UndoableEditSupport() Constructs a new helper for broadcasting UndoableEditEvents.
	UndoableEditSupport(Object realSource) Constructs a new helper for broadcasting UndoableEditEvents.

Method Summary
void	addUndoableEditListener(UndoableEditListener val) Registers a listener.
void	beginUpdate() Starts a (possibly nested) update session.
protected CompoundEdit	createCompoundEdit() Creates a new instance of {@link CompoundEdit}.
void	endUpdate() Ends an update session.
UndoableEditListener[]	getUndoableEditListeners() Returns an array containing the currently registered listeners.
int	getUpdateLevel() Returns the current update level.
void	postEdit(UndoableEdit edit) If {@link #beginUpdate} has been called (so that the current update level is greater than zero), adds the specified edit to {@link #compoundEdit}.
void	removeUndoableEditListener(UndoableEditListener val) Unregisters a listener.
String	toString() Returns a string representation of this object that may be useful for debugging.
protected void	_postEdit(UndoableEdit edit) Notifies all registered listeners that an {@link UndoableEditEvent} has occured.

Field Detail

compoundEdit

protected CompoundEdit compoundEdit

compoundEdit

listeners

protected Vector<UndoableEditListener> listeners

The currently registered listeners.

realSource

protected Object realSource

The source of the broadcast UndoableEditEvents.

updateLevel

protected int updateLevel

The number of times that {@link #beginUpdate()} has been called without a matching call to {@link #endUpdate()}.

Constructor Detail

UndoableEditSupport

public UndoableEditSupport()

Constructs a new helper for broadcasting UndoableEditEvents. The events will indicate the newly constructed UndoableEditSupport instance as their source.

UndoableEditSupport

public UndoableEditSupport(Object realSource)

Constructs a new helper for broadcasting UndoableEditEvents.

Parameters: realSource the source of the UndoableEditEvents that will be broadcast by this helper. If realSource is null, the events will indicate the newly constructed UndoableEditSupport instance as their source.

Method Detail

addUndoableEditListener

public void addUndoableEditListener(UndoableEditListener val)

Registers a listener.

Parameters: val the listener to be added.

beginUpdate

public void beginUpdate()

Starts a (possibly nested) update session. If the current update level is zero, {@link #compoundEdit} is set to the result of the {@link #createCompoundEdit} method. In any case, the update level is increased by one.

Thread Safety: It is safe to call this method from any thread without external synchronization.

createCompoundEdit

protected CompoundEdit createCompoundEdit()

Creates a new instance of {@link CompoundEdit}. Called by {@link #beginUpdate}. If a subclass wants {@link #beginUpdate} to work on a specific {@link #compoundEdit}, it should override this method.

Returns: a newly created instance of {@link CompoundEdit}.

endUpdate

public void endUpdate()

Ends an update session. If the terminated session was the outermost session, {@link #compoundEdit} will receive an end message, and {@link #_postEdit} gets called in order to notify any listeners. Finally, the compoundEdit is discarded.

Thread Safety: It is safe to call this method from any thread without external synchronization.

Parameters: edit the edit action to be posted.

removeUndoableEditListener

public void removeUndoableEditListener(UndoableEditListener val)

Unregisters a listener.

Parameters: val the listener to be removed.

toString

public String toString()

Returns a string representation of this object that may be useful for debugging.

_postEdit

protected void _postEdit(UndoableEdit edit)

Notifies all registered listeners that an {@link UndoableEditEvent} has occured.

Lack of Thread Safety: It is not safe to call this method from concurrent threads, unless the call is protected by a synchronization on this UndoableEditSupport instance.

Parameters: edit the edit action to be posted.