Nested classes allow one class to be defined within another, enabling inner classes to access members of the outer class. There are several types of nested classes: inner classes that can be member, anonymous, or local; and static nested classes. Member inner classes can access outer class members and be invoked from within or outside the outer class. Anonymous inner classes have no name and are created from an abstract class or interface. Local inner classes exist only within a method. Static nested classes can access static members of the outer class but not instance members.

1. Nested Class

2. What is Nested Class?
 Inner classes are class within Class.
 Inner class instance has special relationship with
Outer class. This special relationship gives inner class
access to member of outer class as if they are the
part of outer class.
 Additionally, it can access all the members of outer
class including private data members and methods.

3. Syntax of InnerClass
//outer class
class OuterClass {
//inner class
class InnerClass {
}
}
How to access Inner Class?
 Inner class can be accessed only through live
instance of outer class.

4. Example of InnerClass

5. Types of Nested class:
non-static nested class(inner class)
a)Member inner class
b)Anonymous inner class
c)Local inner class
static nested class

6. Member Inner Class
 A class that is declared inside a class but outside a
method is known as member inner class.
Invocation of Member Inner class
 From within the class
 From outside the class

7. Example of member inner class that is
invoked inside a class

8. Example of member inner class that is
invoked outside a class

9. Anonymous inner class
 A class that have no name is known as anonymous
inner class.
Anonymous class can be created by:
Class (may be abstract class also).
Interface

10. Example of anonymous inner class by
abstract class

11. Example of anonymous inner class by
interface

12. Local inner class
 A class that is created inside a method is known as local
inner class.
 If you want to invoke the methods of local inner class,
you must instantiate this class inside the method.
Rules for Local Inner class
 Local variable can't be private, public or protected.
 Local inner class cannot be invoked from outside the
method.
 Local inner class cannot access non-final local variable.

13. Example of local inner class

14. static nested class
 A static class that is created inside a class is known as
static nested class.
 It can access static data members of outer class
including private.
 static nested class cannot access non-static (instance)
data member or method.

15. Example of static nested class

16. Purpose of nested classes
Nested classes represent a special type of
relationship that is it can access all the members
(data members and methods) of outer class
including private.
Nested classes are used to develop more
readable and maintainable code because it
logically group classes and interfaces in one place
only.
Code Optimization: It requires less code to write.

17. Reference:
 http://www.studytonight.com/java/nested-
classes.php
 http://www.javatpoint.com/difference-between-
nested-classes-and-inner-classes
 http://www.javatpoint.com/annonymous-inner-class
 http://www.javatpoint.com/member-inner-class
 http://examples.javacodegeeks.com/core-
java/class/static-inner-class-example/

18. Thank You!!!