Completely aside from typos and other user-input errors, there's always been an uneasy relationship between displaying formatted numeric text and receiving numeric text input from the same field.

Although the code doesn't focus on extracting regular expressions from a ResourceBundle, it does include a good example of extending the default behavior of the formatted text field.

As it is, though, the code doesn't do anything to make sure that clumsy users or programmer bugs don't cause incorrectly formatted data to be put into the number field.