Debian GNU/Linux Java FAQ.
Footnotes

1

Notably Blackdown's port to Linux of Sun's Java Developer's Toolkit (SDK) or Java's Runtime Environment (JRE). Which you should retrieve from Blackdown, see How can I get Debian packages from Blackdown?, Section 11.1.

2

Use only one of them, it could be potato, woody, testing (sarge) or (unstable) (sid) depending on the Debian release you are running, or it could be testing or unstable if you are running development releases.

3

You need the main archive too since now there is a j2se-common package which resides there. If you had already installed j2sdk when the above dependency did not exist you would get warnings once you do an apt-get update or apt-get upgrade.

4

X will depend on the Java 2 version you are downloading, it can bee 1.2.1, 1.2.2, 1.3 or even 1.4

Debian GNU/Linux Java FAQ.