In a recent announcement, Canonical has specified that Ubuntu Partner Archive will no longer contain Sun JDK, the packages (sun-java6-jre, sun-java6-jdk, sun-java6-plugin, sun-java6-source etc) will be removed on 16th of the next month, due to some licensing problem, as the said in announcement –
we no longer have permission to redistribute new
Java packages as Oracle has retired the “Operating System Distributor License for Java”
Although, it will be remain installed on the systems but no security updates will be provided in future so the ubuntu users who are dependent on Sun JDK or any of this component are recommend to migrate to OpenJDK or Oracle JDK if you get any problem with open JDK in some applications.
Migrating from Sun JDK to Open JDk
Uninstall Sun JDK and its components
sudo apt-get purge sun-java*
Then install OpenJDK 7/6
sudo-apt-get install openjdk-6*
If you want to install only few selected package such as openjdk-6-jre then type
sudo apt-get install openjdk-6-jre