This document is a presentation on nested types in Java prepared by Prof. Ashish Bhatia. It discusses different types of nested classes including top level nested classes, inner classes, local classes, anonymous classes, and enum types. It provides examples and explanations of each nested class type and why nested classes are useful for logical grouping of classes and increasing encapsulation.

1. Prepared Using
Nested Type
For Semester – III [MCA]
August
2012
Prepared by
Prof. Ashish Bhatia
ast.bhatia@gmail.com
ashish@asbspace.in
www.asbspace.in
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2. Note
● This ppt is for teaching purpose only.
● The ppt may contain some material from
books/api documentation/internet.
● No intention of breaking any rights or what so
ever.
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3. Nested Classes
● The class define inside another class are
known as Nested Class.
● Top Level Nested Class
● Inner class is static
● Inner Class
● Local Class
● Anonymous Class
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4. Why we need nested class?
● Logical Grouping of class
● Helper classes
● Increase encapuslation
●
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5. Top Level Nested Class
● Static member class is also known as top level
nested class.
● Member class and enclosing class shares trust
replationship in that they can access each
other memebers, including private members.
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7. Inner Classes
● Non-static member classes.
● Relationship :
● We cannot have an instance of innerclass without
having instance of the outer class.
● Used to represent one to many relationship.
● Eg : Account Class [Outer]and Transaction
class[Inner]
● We cannot have transaction without Account
● Inner class cannot have static members.
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9. Local Class
● Class inside a method, constructor or intializer
block.
● This class donot have access specifier and
cannot be dcelared static / non-static.
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11. Anonymous Class
● Do not have name.
● Defined and created at same place.
● Become part of expression.
● Single inheritance type either extend or
implement
● Always non-abstract.
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12. enum Type
● Java 5 onwards.
● Cannot have super class but can implement
interface.
● Number of instances are fixed.
● ; required after declaration.
● Sub class of Enum
● Instances have name and ordinal value.
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13. enum Type
●
Each instance are static and final.
●
Ordinal Value starts from 0
●
To access Month.January
●
Enum type are comparable [ ordinal]
●
Values and Valuesof
●
public static Month[] values()
●
public static Month valueOf(String n)
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