Welcome to the Ranch
You didn't use the code button correctly, but don't worry: I corrected that and doesn't it look better.
Please always tell us the origin of your code, to prevent copyright problems.
You posted the code and didn't ask a question. You have the bad design feature of fields with the same name in superclass and subclass. That is bound to cause confusion.
Moved to different forum as not a GUI‑related question.
Based on the subject of the topic, I am assuming the question is ... why doesn't the code compile? ... Anyway, it may be a good idea to mention the compiler error, and what you think the issue is. After all, it is easier to learn if you attempt to figure it our yourself.