Personally, I learned coding through college. However, you probably do not have access to any college courses so if you like, I can show you what I know.
Anyway, some java is only useful to learn for making plugins/"abilities". However, other java like GUIs are not useful. GUIs (if you don't already know) are what the user visually sees. A plugin cannot deal with GUIs because it controls the server, not the client; it cannot add new colors and blocks. However, if you learn Java, I would recommend you learn it completely... Not just the parts for a plugin. Learning a programming language can be useful for the rest of your life: even if you do not enter a programming career. Programming can make tools, plugins, hacks, robots, data writers, data sensors, key listeners, calculators, etc. These could all be useful for, say, an architectural engineering degree, aerospace, aerodynamics, physics, biology, chemistry, astronomy, meteorology, etc. Overall, you should not take any shortcuts when learning to program. And like I said earlier, I can help you start off in programming java.
My take on learning from YouTube:
Learning from YouTube is honestly not the best way to learn java. Reading a website, book, or being taught by an instructor while programming at the same time small programs that demonstrate what you are learning is the best way to learn because you are memorizing and solidifying what you just learned by showing yourself that you can so the same kind of thing. So I would recommend getting started from a non-YouTube source. Maybe do some YouTube when you understand the basics... but not until then.
Java's Library of awesome tools:
When you download java, the reason it is so big is because java has a HUGE library of tools that are all very simple to use. Due to their immense size, I highly doubt anyone has memorized all the names and all the tools that are available. Even I still use the internet to learn about them when I forget how to use something. This library is where the tools for building GUIs are kept. When beginning java, you will learn the most basic of these files, then you will more and more until you do not need guides anymore, and can just learn through Oracle's documentation of these. That is when I believe is when you can branch into programming plugins. Sadly, this will take a lot of time, but it is all worth it not just for fun right now, but in the future as we'll.
