Can you guys recommend me free Java courses?

why would you need a course for that? it is all out there and for free.

Type java course on your favorite search engine, open few results on new tabs, try them then stick to the one you find most useful.

Or if you know the basics, start developing a project and search your problem when you are stuck.

The New Boston’s should be ok if you are a beginner, otherwise any free Java book (plenty if you google)

I'll find you a free course for $100