java compiler "sdk" ?

[Justin Conover]

I'm starting to learn java and I'm a little confused with all the java
"stuff" in rawhide, is:

# yum info gcc-java.x86_64
Installed Packages
Name   : gcc-java
Arch   : x86_64
Version: 4.0.0
Release: 5
Size   : 5.3 M
Repo   : installed
Summary: Java support for gcc.

Description:
 The gcc-java package adds experimental support for compiling Java(TM)
programs and bytecode into native code. To do this, you will also need
to install the Java runtime library included in the gcc-libgcj
package.

Comparable to Sun's j2sdk?

What would I use to learn/compile java code?

TIA