Chapter -18 What is Inner Class(Nested Class) in Java

 

Inner/ Nested Class in Java

Introduction of java Inner Class: 

• Java inner class or nested class is a class that is declared inside the class or interface.
• Next Unit Discuss details in class and interface with opp all topics. 
• When a class is used inside the body of the another class then is used inside the body of another class then this concept is called inner class concept.
• Just like nested-if and nested-loop one class inside another class is called nested class. 
• Inner class represent a particular type of relationship that is access all members of data-members and members functions of the outer class.  
• Inner class provide write less code. 
• It is also called nesting of class. 

Syntax:- 

Example : 

• For better understanding of inner class see the below example

//  Example 1: Find add program using inner class.

class OuterAdd{         //Create OuterClass

    public void outadd(){       // create outer methods

        int a=10, b=20, c;

        c=a+b;

        System.out.println("Addition of Outer Class Value: "+c);

    }

    class InnerAdd{     //create InnerClass

        public void inadd(){        // create inner methods

            int x=5, y=8, z;

            z=x+y;

            System.out.println("Addition of Inner Class Value: "+z);

        }

    }

}

class Inner{    // Create main function

    public static void main(String args[]){

       OuterAdd obj=new OuterAdd();

        obj.outadd();

        OuterAdd.InnerAdd obj1= obj.new InnerAdd();

        obj1.inadd();

    }

}

Explanation:- 

• In this example explanation  just focus on creating the instance(object) of InnerAdd class you got something new. 
• The Object of InnerAdd is creating with the reference of OuterAdd because InnerAdd exists inside of OuterAdd.

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UNIT-2 JAVA