Hello, you can use rxtx to implement programs such as serial port debugging assistant. If you want to create an interface, you can also combine it with interface libraries such as JFace and Swing.

I don’t have any ready-made programs now. I used this library in a competition a few years ago. There is a blog here that talks pretty well. It can at least guide you to achieve your needs and provides a demo for reference only.
Java uses open source Rxtx to implement serial communication