New to Java

I'm teaching myself Java from one of the Sams books (Teach yourself Java in 21 days). I don't think I want to try learning an IDE at the same time, because it might be too much, so I'm going to use the JDK. I know that my Mac came with the JDK, and I want to ask if it has everything I need -- the book says I need a compiler, interpreter, debugger, file and archiving program, and several others. Can anyone out there tell me if I've got all that's necessary, and if not, how do I know what I need and don't, and where I can get them (I assume from the Java site, but I don't know where to look).

At the command line in Terminal, when I enter java -version, this is what I get:

java version "1.6.0_07"
Java(TM) SE Runtime Environment (build 1.6.0_07-b06-153)
Java HotSpot(TM) 64-Bit Server VM (build 1.6.0_07-b06-57, mixed mode)

I noticed there are other updates to the JDK on the Java site, but I can't find anything that's for Mac OS X, only windows, linux and Solaris.

Thanks for all your help