This is a list of links to some of my answers on Stack Overflow that contain small, yet complete runnable Swing apps. Most of the answers have images (or GIFs) so you can see what the app does. You should be able to just copy/paste/run the code.
Enjoy and please feel free to contact me with any questions. But note that I no longer use Swing, and have not used it in a while. So I may not be able to answer some questions regarding the code.