Erm... You didn't ask for resources to learn Spigot plugin development You asked for resources to learn Java (Which I do suggest learning first. Don't just jump right into Spigot)
your wording was correct, your thought process was not. You must learn math before calculus You must learn how to walk before running and the same deals with this situation You must learn Java before learning how to make Spigot plugins
Read books such as Big Java. They're incredibly resourceful and used to teach Java classes in colleges. All these Youtube videos teach you is how to copy/paste without any true knowledge about how the resource you're utilizing works. For instance, a HashMap. Many here probably just assume "It work good, i use" but what they don't seem to know is it's constant time and computes hashtable indexes using the keys hashcode. That's incredibly important to know when attempting to create an efficient program/plugin but you'll never learn such things from these low level bukkit plugin tutorials. You could also just take a class in some community college. They also offer other classes such as data structures and software development (most of the time..).
CodeCademy they'll save your butt. but don't forget https://docs.oracle.com/javase/tutorial/java/javaOO/index.html if you want more informational.
I don't think so. He wanted to jumped with spigot development so the one he's looking for was to learn java program.
