Few questions

Hai thar /prog/  I'm 15, going into sophmore year of highschool, and getting to be decent with computers.  My last 2 computers have been built by me, I've done some game modding/scripting(Major TES fan), and I succesfully tri-boot gentoo lunix, freebsd, and XP.  Overall, I know a pretty decent amount of my shit, and I've just recently started getting into programming.  I've started out by learning Java, mainly because I want to take the AP exam for Comp Sci, and that means Java.  I bought a book to learn the language, and a review book for the actual exam.  My question, has anyone here taken the AP Comp Sci A or AB exams recently?  Suggestions?  Java isn't the most popular language from what I gather, so what should I learn after that?

I find that the most difficult part of programming is keeping track of what I'm doing. Many times I've been working on a different section of my program only to find that I've completely forgotten how another part of it works. Good commenting and abstraction helps, of course, but I'm so forgetful. It's incredibly frustrating.