This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
I don't actually know what's going wrong with your code, but you might consider creating your own implementation of ListModel, which is pretty easy and straightforward if you extend AbstractListModel. Then, keep a reference to the list model in your surrounding code, and you can do the updates easily.