It’s hard if you have unprotected, shared mutable state. If you use a language that uses immutable data structures (Haskell, Clojure, Erlang) it’s easy! If you use a language that won’t let you share mutable data without the required protection (Rust) it’s also easy! Everything else and you can be sure that even if it looks like it works, it most likely doesn’t.

Wow, no one mentioning IntelliJ?? I use the free edition with Rust and it works great… the only thing missing is a debugger, which requires the CLion distribution which is not free… but so far that hasn’t been a big problem for me.

When I was still at university, I started working on a place where Spring was used… they gave me a book called “Spring in Action” to read. I loved reading it and everything made much more sense after that… I highly recommend trying to get a deep understanding of something so central to an application like Spring before you start doing anything more advanced with it. You wouldn’t want to drive a F1 car without first learning how to do it properly, it may be fun at first but you’re likely to crash and burn.

In Java it’s really rare to see hundreds of files in a single package (dir)… do you have examples showing anything different??