Anyone know how to do a Grid Layout for Sudoku code defining the sub blocks?

Hi Guys,
Basically, I'm writing a Sudoku solver and its the first time I've come into contact with the interface package SWING in Java. so far I've been using a 9x9 "GridLayout" within a "JPanel" dispalying "JTextFields" (blank so far!)...I'd like to make it so that there is a definition between the sub blocks(3x3 matrices) and I can't work it out. Does anyone know how to insert a GridLayout inside a GridLayout? Then, I would have a 3x3 in the Panel and 9 3x3's within the first grid cells :-s..or if anyone could think of a better idea that would be great ...

Thanks
Sarah