If you would like to install Sun Java SDK, you have to use "partner" repository.
sudo add-apt-repository "deb http://archive.canonical.com/ lucid partner"
sudo apt-get update
sudo apt-get install sun-java6-jdk
Is that all? Not quitely.
Choosing the default Java to use
Just installing new Java flavours does not change the default Java pointed to by /usr/bin/java. You must explicitly set this:
* Open a Terminal window
* Run sudo update-java-alternatives -l to see the current configuration and possibilities.
* Run sudo update-java-alternatives -s XXXX to set the XXX java version as default. For Sun Java 6 this would be sudo update-java-alternatives -s java-6-sun
* Run java -version to ensure that the correct version is being called.
You can also use the following command to interactively make the change;
* Open a Terminal window
* Run sudo update-alternatives --config java
* Follow the onscreen prompt
Ref: https://help.ubuntu.com/community/Java
