As /u/goto-reddit said, JavaScript and Java are fundamentally two completely different languages, albeit they might look similar.

However, there’s more to programming than just choosing a language and while I’m not an expert on Java, you might still find my thoughts on the matter useful to some degree.

Let me start with saying that I don’t think “coding is a breeze” to anybody unless they already spent time programming and/or thinking like a programmer, and even then, from my experience, it’s just that problems become more abstract/complex, e.g. instead of bashing your head trying to figure out why this piece of code does this stupid shit, you spend a night trying to figure out if a particular problem is solvable and how it can be solved with what you have, or how the hell do you integrate that solution into the old and convoluted code base.

So, the first thing is to realize that you are not somehow special in your inability to fully understand specific code or concept and be able to apply it immediately — each programmer goes through that stage. In fact, I’d wager that truly great programmers become great through their ability to constantly find something that they can’t understand and keep playing with it until they figure it out.

The important words in that last sentence is “keep playing” — persistence and exploration are huge parts of actually understanding anything. It might be OK to just construct 20 different arrays to understand the syntax (i.e. how to use arrays), but if you want to understand why and when to use arrays that won’t cut it.

You need an actual real-world problem that involves what you want. Unfortunately, I rarely hear universities providing students with such mini-projects, so it’s up to you to come up with one — it just has to be fairly complex (something that could be applied to your day-to-day life), theoretically solvable, and be interesting enough for you to keep at it during hard times (since there will be plenty of those).

Completing this project isn't the main goal, main goal is to see how all the programming pieces (syntax, frameworks/libraries, algorithms, data structures, etc.) fit into a working system and interact together to solve something.

And again, programming/CS is one of those fields where your persistence means way more than your previous experience/predispositions.

Hope it was at least somewhat helpful and good luck on your journey!