[R] installing java on ubuntu 11.10 installation

[ravi]

Dear list members,
I am starting to get acquainted with linux on a ubuntu 11.10 installation on an external hard disk. I have just installed R and all the packages available in the r-cran-* list. Now, I would like to get on with the installation of packages like Deducer and Acinonyx. The former requires JGR which in turn requires Java. I have tried to follow the instructions available at the following link on the R wiki :
http://rwiki.sciviews.org/doku.php?id=getting-started:installation:debian

which in turn points at : http://rosuda.org/JGR/linux

But these instructions do not seem to have worked. I get the following output :
ravi at raviM1330:~$ java -version
The program 'java' can be found in the following packages:
 * gcj-4.4-jre-headless
 * gcj-4.6-jre-headless
 * openjdk-6-jre-headless
 * gcj-4.5-jre-headless
 * openjdk-7-jre-headless
Try: sudo apt-get install <selected package>
ravi at raviM1330:~$ 


I would like to know how I should install java. Is it preferable to install the sun jdk version or the open jdk? By doing a search on R seek, I don't see any instructions on  the currently valid procedure for installiing java. I would appreciate getting help on installation and sufficient configuration. Also, on first uninstalling whatever I have installed with the command :
sudo apt-get install sun-java*
Before this, I tried with :

sudo apt-get install sun-java6-jdk
But nothing seemed to happen after this (as far as I can remember). 

Thanks,
Ravi