[JAVA]I made a very basic program with the help of this subreddit and the resources I found browsing through. I'd like some insight on what I can do better. Any comment or criticism would be great!

I made a little world capital quiz. The GUI is terrible and the code is probably very poorly written, but I am proud of it. Here is the code! Warning: it's pretty long. I want to create a program with the same functionality, but using Java graphics rather than the JFrame GUI. I have no idea how to do this, so if anyone knows how to do it/knows of a good online resource, please tell me! Thanks.