Updated: April 17, 2015
As you may or may not know, in the last couple of years, the Linux community has largely switched from Oracle Java to OpenJDK. This means you can still run and execute Java applets on your system and in your browsers, but not using Oracle's plugins.
However, some sites, especially game portals, require the use of Oracle Java, which presents you, as the Linux user, with a problem. Indeed, I faced this little hurdle a while back, and I decided to write a tutorial, explaining how you can install Oracle Java on modern versions of Linux, in this case Xubuntu, side by side with the default offering. Follow me.
Task at hand
All right, let's begin. You will need to add an extra PPA, specifically the one maintained by WebUpd8. In general, this site as well as its repo are a good source of useful info related to Ubuntu. Add the new source and refresh the contents:
sudo apt-get install python-software-properties
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
Then, install Oracle Java - the latest version is Java 8:
sudo apt-get install oracle-java8-installer
Once this step is complete, Java is installed. The only thing you may want to do is run the Java configuration tool to select the default version. You will have the option to choose between OpenJDK and Oracle Java. The installer will mark the new software as the default one.
sudo update-alternatives --config java
After this, open your browser(s) and check. If you can find the Java plugin, then all is well. You can indeed identify it by the version number, but if this is a little tricky, you can open the about:plugins page for more details. Job done - Orc peasant voice style.
This is a very simple tutorial. Most people will never need to bother, but sometimes games, bank sites, government portals, other official entities, and an odd site here and there might actually force you to use Oracle Java, just as some PDF documents are only designed for Adobe Reader. If this is the case, you have the way of getting the necessary software.
We dabbled a little in configuring additional software sources, installing new programs, tweaking the default Java version, and learned how to check the status of our plugins in the browser. All in all, most likely it wasn't a waste of 10 minutes in your afternoon reading session. See you around.