Most Linux distributions come with some form of OpenJDK installed, but if you want to use the real Java you have to go to the trouble of manually installing it. Unless, of course, you let Javinstall take care of this for you. Javinstall is a customized graphical installer that makes installing Oracle's Java platform in Linux extremely easy. Download the latest stable executable version at http://sites.google.com/site/javinstall. If you know C++ and Qt, please check out the code and see if there's anything you would change. I created the original version in just two days, and it's one of my first C++ applications, so it goes without saying that the project would benefit from a patch or two. Javinstall is under the MIT license.
alexreidy/Javinstall
Javinstall makes installing Oracle's Java platform (JRE/JDK) in Linux extremely easy
C++MIT