I always forget that Debian doesn’t include the Sun JDKs in its default repositories.. Its easy to get though:

Just edit /etc/apt/sources.list and add these lines at the end of the file:

deb http://ftp.debian.org/debian unstable non-free
deb-src http://ftp.debian.org/debian unstable non-free

This gives you the packages not meeting Debian’s open source criteria. Now just run sudo apt-get update and sudo apt-get install sun-java6-jdk to get your Java on. You might want to stick around your console too since you have to accept the license agreement during the install.