Replacing the OpenJDK with the Oracle JDK
Follow these instructions to add the source to your repositories.
In a terminal run:
sudo apt-get updatesudo apt-get install update-sun-jre-
sudo update-alternatives --config firefox-javaplugin.soand select the one that's in/opt(This enables Sun Java in Firefox)
With this package you don't have to worry about constantly checking for updates. The maintainer takes good care to keep it current for you. It also adds all the update-alternatives links for you, so it's a lot less work than the above comment on your question.