This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Static initialization blocks - which is what you have beginning at lines 3 and 15 - are run when the class is loaded. So that's usually at the first point a reference is made to it. In this case, it will run before the main method does. The StaticTests class has to be loaded before any of its methods can be run, and that causes all its superclasses to be loaded as well.