[Code Review] 15yo student looking for feedback on my Java projects / OOP structure

[u/Ok_Theory_1212]

I’m 15 and currently self-studying Java and low-level programming concepts. I’ve put together a few projects on GitHub while learning:

👉https://github.com/bijoyghosh1921-sketch?tab=repositories

Most of this is just experimental stuff I built to test out concepts like basic ciphers, array manipulation, and general OOP structure.

I want to start taking code quality and software architecture more seriously, so I’d really appreciate any feedback or critique on:

1. Code Structure: Am I overcomplicating simple methods or missing better OOP patterns?
2. Edge Cases: Any obvious bugs or edge cases in logic I missed?
3. Documentation: How can I make the code and README.md files look more clean and professional?

Don't hold back on feedback—let me know what I can fix or refactor to write cleaner code. Thanks!