Classes and Types
A type can be considered to be a restriction on the set of
values that a variable is permitted to store.
A class can be used as a type.
  String name = "Washington";
 Cube myBlock = new Cube(10);
In Java, there are four primitive types that are not classes:
  int,  float,   double,   boolean.
These permit “lightweight” values to be used, which can be
stored and manipulated more efficiently than can bona fide
objects.