We have already posted about sun java was moved to the Partner repository in Ubuntu 10.04 (Lucid)
Procedure to follow
Open terminal and run the following commands
Add partner repository using the following command
sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"
Update the source list
sudo apt-get update
Now install sun java packages using the following commands
sudo apt-get install sun-java6-jre sun-java6-plugin sun-java6-fonts
The above command will download all the required packages and begins the installation, you’ll get a screen that contains the Sun Operating System Distributor License for Java and hit Enter to continue.
You’ll see a dialog that asks you if you agree with the DLJ license terms. Select Yes, and hit Enter; the JRE will finish installing.
Testing Java Runtime Environment
You’ll want to confirm that your system is configured properly for Sun’s JRE. This is a two-step process.
First, check that the JRE is properly installed by running the following command from a terminal.