Do I need to have Java installed on my machine? The website (Blackboard) that my school uses says that I need to have Java installed, but everything seems to be working fine without it. Running Ubuntu 12.04 64bit, default Firefox browser.
The site is probably just checking for Oracle's implementation of Java and since it does not find it it complains you need to install it.
That happens a lot with bad programmed sites that require Java, ie: one of those seems to be my NAS web interface, everything works the same as my Windows laptop with Oracle Java, nothing is different, still it complains I need Java installed
If everything is running then that is a sign you have Java (probably the open source OpenJDK implementation) and if you have no complaints I would say its more than save to ignore the warnings you get.
Make sure you tick any box with the option Don't annoy me again and move on, you can start thinking about it if anything seems wrong later on.