Reflection - The Java Programming Language - page 593

Returns the Class object on which it is invoked, after casting
it to represent a subclass of the given Class object. If the cur-
rent Class object does not represent a type that is a subtype
of subType 's type (or subType itself), then ClassCastException is
thrown.
The asSubclass method doesn't change the Class object at all; it simply
changes the type of the expression it is invoked on, so we can use the
additional type informationjust as a cast does. For example, here's how
you can use asSubclass with forName to fix the previous problem:
Class<? extends String> c3 =
Class.forName("java.lang.String").
asSubclass(String.class); // OK
Note that you can't convert the unknown type token to be exactly
Class<String> , but having Class<?extends String> should be sufficient. Of
course, String is not a practical example for using reflection. A more
typical example would be when you are loading an unknown class that
implements a known interface and you want to create an instance of
that class; you'll see an example of this in the Game class on page 436 .
16.1.2. Class Inspection
The Class class provides a number of methods for obtaining information
about a particular class. Some of these provide information on the type
of the classthe interfaces it implements, the class it extendsand others
return information on the members of the class, including nested classes
and interfaces. You can ask if a class represents an interface or an array,
or whether a particular object is an instance of that class. We look at
these different methods over the next few pages.
The most basic Class methods are those that walk the type hierarchy,
displaying information about the interfaces implemented and the classes