Declarations, Initialization, and Scoping - SCJP Sun Certified Programmer for Java Platform SE6 - page 163

In other words, a static nested class is not really much different than a top-level class
except for a few subtle benefi ts:
The nesting creates a type of namespace. To denote a nested class from outside its
enclosing class, the nested class is prefixed with the name of the enclosing class (similar
to how static fields and methods are accessed).
Access to the nested class can be controlled by an access specifier. For example, a
nested class declared as private can only be used within its enclosing class, in effect
hiding it from any other classes.
The enclosing class has access to the fields and methods of the nested class, even the
private ones.
Let's look at an example. The following Box class is nested within Shipment :
1. import java.awt.Dimension;
2.
3. public class Shipment {
4. public static class Box {
5. public Dimension dimension;
6. public int depth;
7.
8. public Box(Dimension d, int x) {
9. dimension = d;
10. depth = x;
11. }
12.
13. public int getVolume() {
14. return dimension.height * dimension.width * depth;
15. }
16. }
17.
18. public Box box;
19.}
Even though Box is defi ned inside Shipment , because Box is static it can be used like
any other top-level class. The syntax for referring to Box outside of Shipment is Shipment
.Box . The following Shoe class declares a fi eld of type Shipment.Box and initializes the fi eld
in its constructor. See if you can determine the output of running the main method in Shoe :
1. import java.awt.Dimension;
2.
3. public class Shoe {
4. public Shipment.Box box;
5.