The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.
See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.
Undoable edit events occur when an operation that can be undone occurs on a component. Currently, only text components fire undoable edit events, and then only indirectly. The text component's document fires the events. For text components, undoable operations include inserting characters, deleting characters, and modifying the style of text. Programs typically listen to undoable edit events to assist in the implementation of undo and redo commands.
Here is the undoable edit event handling code from an application called TextComponentDemo
.
... //where initialization occurs document.addUndoableEditListener(new MyUndoableEditListener()); ... protected class MyUndoableEditListener implements UndoableEditListener { public void undoableEditHappened(UndoableEditEvent e) { //Remember the edit and update the menus undo.addEdit(e.getEdit()); undoAction.updateUndoState(); redoAction.updateRedoState(); } }
You can find a link to the source file for TextComponentDemo
in the
example index for Using Swing Components. For a discussion about the undoable edit listener aspect of the program see
Implementing Undo and Redo
The UndoableEditListener Interface
Because UndoableEditListener
has only one method, it has no corresponding adapter class.
Method | Purpose |
---|---|
undoableEditHappened(UndoableEditEvent) | Called when an undoable event occurs on the listened-to component. |
Method | Purpose |
---|---|
Object getSource() (in java.util.EventObject ) |
Return the object that fired the event. |
UndoableEdit getEdit() | Returns an
UndoableEdit object that represents the edit that occurred and contains information about and commands for undoing or redoing the edit. |
The following table lists the examples that use undoable edit listeners.
Example | Where Described | Notes |
---|---|---|
TextComponentDemo |
Implementing Undo and Redo | Implements undo and redo on a text pane with help from an undoable edit listener. |