You can also use minime: http://code.google.com/p/minime/
It's an open source GUI library for j2me. miniME works on canvas level (lowest level in j2me) to draw every control so your UI will look exactly the same whatever the handset it'll be running on. Other advantage are:
- miniME uses its own event loop to manage user controlled event (botton pressed, softbar, ..), so you Application will "behave" the same whatever the handset.
- miniME support the concept of Views and stack of view, in order to make navigation between different view/screens very easy.
Here is an example: A View is what you have on the screen at a given moment (for example the main menu screen), then to go to a sub menu, you create a new view, and by calling a simple API, you push it in the stack of Views. The previous view (the main menu) is still existing, but inactive. When the sub menu view complete his work (for example, user press back, or do a selection), you can just go back to the previous view by calling a pop api.