Debian Linux "Sarge" - Trouble installing jar: No Java?

[jamez1988]

I'm trying to play Wyvern (http://www.cabochon.com/) in Linux.
The instructions on the website say to download "install.jar" and then run the command "java -jar install.jar" to install.
I downloaded the file and ran that command as root.
I get a message saying "bash: java: command not found".
I *think* I have the required java packages installed on my system. What packages do I need for the Java command? (I did a search, but theres so many packages, its not even funny)

update: I *thought* I had the correct java packages installed, but firefox thinks I don't. I'm getting confused. If I don't have java installed, what are all these java packages?

[deathadder]

To get the java command working go to java.sun.com and download the sdk package for linux, and install it. After you will need to update your path.

To check to see if you already have it install you can run 'whereis java' it will return a path. You can either add that to your path or use the full path for the command.

[jamez1988]

the "whereis java" command returned "java: /usr/share/java"
I'm not familier with paths in linux. What file do I need to modify?

update: I just visited the usr/share/java folder, and all that is there is a file named "kjc.jar'.
Does this mean it's not installed after all?

update on the update: I installed Java, and it worked! Now all I have to do is get this stupid after-install launcher working. You'd think there would be an easier way to do this. arugh.