Class UndoableEditSupport

protected CompoundEdit compoundEdit

compoundEdit

protected Vector listeners

The currently registered listeners.

protected Object realSource

The source of the broadcast UndoableEditEvents.

protected int updateLevel

The number of times that beginUpdate() has been called without a matching call to endUpdate().

public UndoableEditSupport()

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

See Also:

UndoableEditSupport(Object)

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.

protected void _postEdit(UndoableEdit edit)

Notifies all registered listeners that an 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.

public void addUndoableEditListener(UndoableEditListener val)

Registers a listener.

Parameters:

val - the listener to be added.

public void beginUpdate()

Starts a (possibly nested) update session. If the current update level is zero, compoundEdit is set to the result of the 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.

protected CompoundEdit createCompoundEdit()

Creates a new instance of CompoundEdit. Called by beginUpdate(). If a subclass wants beginUpdate() to work on a specific compoundEdit, it should override this method.

Returns:

a newly created instance of CompoundEdit.

public void endUpdate()

Ends an update session. If the terminated session was the outermost session, compoundEdit will receive an end message, and _postEdit(UndoableEdit) 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.

public UndoableEditListener[] getUndoableEditListeners()

Returns an array containing the currently registered listeners.

public int getUpdateLevel()

Returns the current update level.

public void postEdit(UndoableEdit edit)

If beginUpdate() has been called (so that the current update level is greater than zero), adds the specified edit to compoundEdit. Otherwise, notify listeners of the edit by calling _postEdit(UndoableEdit).

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

Parameters:

edit - the edit action to be posted.

public void removeUndoableEditListener(UndoableEditListener val)

Unregisters a listener.

Parameters:

val - the listener to be removed.

public String toString()

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

Overrides:

toString in interface Object