I wouldn't recommend Kawa to anybody. It isn't maintained by anybody,
and doesn't support stuff since 1.3.*. University of Queensland uses
Kawa to teach Java with, and it is a totaly horrible experiance for new
coders. They would be better off with UltraEdit. At least until they
change to teaching Scheme :(

If you want to buy a really nice IDE that isn't too expensive get
IntelliJ IDEA from Jetbrains. It is pretty much as fully featured as
most programmers can want, and it only costs US$100.

Netbeans (Sun One Studio) and Eclipse are ok. Netbeans is trying really
hard to be as good as either Eclipse and IntelliJ but not quite getting
there (at least in my opinion). Eclipse is (at least to me) kind of
weird compared to IntelliJ.

Of course this is totally biased ... I really like IntelliJ IDEA, I used
to use Eclipse and Netbeans but I didn't really like either. IDEA is
like programming with someone else to help you :)