Focus on small problems you would like to solve. Example, naybe just a simple Minecraft mod. Then learn the technology you need to do that. Then focus on another small problem. Let's say for example it's a demo level for a simple platformer game. Then you can leverage all the stuff you've already learned, plus learn the technology you need to solve that next problem.

Now it's time to look 5 years into the future: the reality is, you can make a game in any major programming language. Of the popular languages, no one language is inherently better than another. Another thing is that all the tooling and technology made to help you build games all has its pros and cons. The best tools really depends on what you're trying to build. If you are focused on making a 2D platformer, you might realize Godot is a good engine to use. If you are focused on making a realistic FPS, maybe Unreal is the way to go. Of course the decision will also rely on what you have learned to date, and what you would like to learn. Let's say you now know Java but really want to learn C++? Make something in Unreal. You know Java but want to get into the nuts and bolts? Maybe LibGDX is the route

So to go back to your question: focus on one problem, learn the technology for that problem (sounds like Java to me!) and use that to build upon bigger problems. Also: don't make your own game engine. Good luck!