556 Chapter 12 Support for Object-Oriented Programming
example, suppose the outer class creates an instance of the inner class with the
following statement:myInner = this.new Inner();Then, if the inner class defines a variable named sum, it can be referenced in
the outer class as myInner.sum.
An instance of a nested class can only exist within an instance of its nesting
class. Nested classes can also be anonymous. Anonymous nested classes have
complex syntax but are really only an abbreviated way to define a class that is
used from just one location. An example of an anonymous nested class appears
in Chapter 14.
A local nested class is defined in a method of its nesting class. Local
nested classes are never defined with an access specifier (private or public).
Their scope is always limited to their nesting class. A method in a local nested
class can access the variables defined in its nesting class and the final variables
defined in the method in which the local nested class is defined. The members
of a local nested class are visible only in the method in which the local nested
class is defined.12.7.5 Evaluation
Java’s design for supporting object-oriented programming is similar to that of
C++, but it employs more consistent adherence to object-oriented principles.
Java does not allow parentless classes and uses dynamic binding as the “normal”
way to bind method calls to method definitions. This, of course, increases
execution time slightly over languages in which many method bindings are
static. At the time this design decision was made, however, most Java programs
were interpreted, so interpretation time made the extra binding time insignifi-
cant. Access control for the contents of a class definition are rather simple when
compared with the jungle of access controls of C++, ranging from derivation
controls to friend functions. Finally, Java uses interfaces to provide a form of
support for multiple inheritance, which does not have all of the drawbacks of
actual multiple inheritance.12.8 Support for Object-Oriented Programming in C
C#’s support for object-oriented programming is similar to that of Java.12.8.1 General Characteristics
C# includes both classes and structs, with the classes being very similar to Java’s
classes and the structs being somewhat less powerful stack-dynamic constructs.
One important difference is that structs are value types; that is, they are stack