Fortunately, many of the common functions are the same. The main difference is the case. The transition has been easier than I thought, which is surprising as I'm not even using an editor with autocomplete. I've been using Notepad++ because I fucking
hate Eclipse and NetBean (to be fair, I've only used them to edit PHP, but I honestly can't see their incredibly intrusive, borderline-obnoxious, and virtually unconfigurable auto-correction being any better with Java, even if it is made for it).
And yeah, Minecraft's code is obfuscated. Fortunately, there is a package called the
Minecraft Coder's Pack that makes developing it much easier. It's a Python-based set of development tools that deobfuscates much of Minecraft's source code, provides you with a means of testing your code outside of your live %appdata%\.minecraft directory, and allows you to easily reobfuscate the code, even splitting off the class files that changed so that you could easily package and distribute them. It's fantastic.
I'm still holding out for the official mod development kit, if that ever comes to fruition. One of my motivations for using source control (Mercurial, because it rocks the shit out of CVS/SVN...Git's cool, too) is because I'm too lazy to use
patch. :p