There are a few types of GUI that don't give you ids for controls, almost all Java toolkits are an example of that.
There are several methods of automating them still:
Assuming the window is always the same size (which is often a pretty safe assumption to make) then AutoIt will allow you to click the window at a given position, or send text just to that window. For example in the above case you could try the following code:
ControlSend("Window Title", "", "", "MyUsername{TAB}MyPassword{ENTER}")
Another solution is using accessibility features. If you google 'autoit java accessibility bridge' I'm sure you'll get some results like this one. I've never tried this personally.
- There is also a java access bridge no idea how this works either, but other people have been using it for a while.
As a last resort, you have to mimic user mouse and keyboard actions. This really isn't the best solution but at least you can be very sure it will work.