A Closer Look at Methods and Classes - Java: A Beginner's Guide - page 281

For example, in the following class, the static method valDivDenom( ) is illegal:
Here, denom is a normal instance variable that cannot be accessed within a static method.
Static Blocks
Sometimes a class will require some type of initialization before it is ready to create ob-
jects. For example, it might need to establish a connection to a remote site. It also might
need to initialize certain static variables before any of the class' static methods are used.
To handle these types of situations, Java allows you to declare a static block. A static block
is executed when the class is first loaded. Thus, it is executed before the class can be used
for any other purpose. Here is an example of a static block: