Java

Java is an object oriented programming language (OOP) developed by Sun.

To figure out if you have it installed, open the command line and type java. If it says something like 'file not found' it looks like you need to download java

Maybe an easier way to check out if you already have java installed is by checkin out the the online demo of BlinkenApplet.

Download
download java ("J2SE v 1.4.2_10 - The J2SE Java Runtime Environment (JRE) allows end-users to run Java applications." is ok).

see Category:Java