How to track and find changes in StyledDocument

Question

Hello everybody!
My name's yoni. I'm new to the forum, but consider myself an intermediate level programmer.
To the matter at hand- I have a document which extends DefaultStyledDocument. I'm trying to implement syntax highlighting for the document (which works, BTW), but my problem is this:
How do I track each and every change (i.e. every char inserted or removed, etc) and more importantly- tell where it happened in the document?
I tried using fireInsertUpdate, fireRemoveUpdate as bases, but they only fire from my document when I press ENTER in editor.
I tried fireChangedUpdate, but it wouldn't fire on every typing, but only when the former 2 fires went up.
Finally I thought of using fireUndoableEditUpdate, which I found DOES fire each and every time I change the smallest thing in the document, but I can't seem to be able to find WHERE in the document this happens.
The bit of code which TRIES to do this is:
protected void fireUndoableEditUpdate(UndoableEditEvent uee)
if(tokenMarker != null) {
javax.swing.undo.UndoableEdit ue = uee.getEdit();
if (ue != null)
if (ue instanceof AbstractDocument.DefaultDocumentEvent)
DocumentEvent dde = (DocumentEvent) ue;
DocumentEvent.ElementChange ch = dde.getChange(getDefaultRootElement());
if(ch != null) { /*************/
tokenizeLines(ch.getIndex() , 1); //tokenizing
markLineStyles(ch.getIndex() + 1); // changing attributes of document 4 syntax highlighting
super.fireUndoableEditUpdate(uee);
What happens is everything works as I expect, except EVERY TIME ch == null for some reason unknown to me.
Any ideas will be appreciated.
Thanks, yoni

Answer 1

I'm not sure I understand exactly what you are asking for so here are a couple of suggestions:
a) undo/redo is supported automatically. See this section from the Swing tutorial:
http://java.sun.com/docs/books/tutorial/uiswing/components/generaltext.html
b) insertString()/remove() methods of the Document are called whenever changes are made to the Document (see above link)
c) add a DocumentListener to the Document to listen for changes:
http://java.sun.com/docs/books/tutorial/uiswing/events/documentlistener.html