r/javahelp

Hello everyone,

At work, we use software developed in Java. This software isn’t protected, it was developed in-house. We’ve lost all contact with the person who created it.

We’d like to make a few changes to the software’s interface for local use. As I know nothing about Java, this project would also be an opportunity for me to learn.

The software comes in the form of an .exe file which can actually be opened like a .zip file and contains folders and .class files.

I don’t know how to properly decompile the entire programme, modify the code, and then recompile it. I’ve seen that can decompile properly, which helped me study the code a bit, so I now know where to make the changes, but that site doesn’t handle modifying or recompiling the code.

Could you recommend a programme (web-based or to install) (preferably free) for decompiling, modifying and then recompiling?

Thank you for your help !

I want to become a strong backend engineer and I’m planning to learn Java deeply along with Spring Boot and Microservices architecture.

There are so many courses and playlists online that I’m confused about what’s actually worth following seriously for long-term growth.

I’m looking for recommendations for:

Core Java

Advanced Java

Spring Boot

Microservices

MySQL/Database design

Backend engineering fundamentals

Industry-level project building

I don’t just want tutorial-level knowledge. I want resources that help build strong engineering fundamentals and real-world backend skills.

Would love recommendations for:

Best YouTube channels

Paid courses

Books

Roadmaps

Any underrated resources

Also, should I focus more on:

Java + Spring ecosystem deeply or

Full-stack development with many technologies?

Would appreciate guidance from experienced backend engineers.

I have learnt java streams and lambda about 2-3 times now. I always keep forgetting how to use it.

How can i learn it, so I won't forget.

Any resources or techniques you've used would help.

Thanks!