I've said this before but I'll keep on saying it until I'm blue in the face: a visual designer is categorically
NOT a beginner's tool. It's only worth investing the time and effort to learn how to do things correctly in a visual designer if you are aiming for a career in GUI design.
Lear to program a Swing GUI the easy way:
Trail: Creating a GUI With JFC/Swing
That said, the order of methods in a class doesn't affect how the code executes. If you think it does, you have other gaps in your learning that you need to make good before progressing to GUIs.