Shadowing Concept in OOPs

 

The following Code has been written in C#

Basic Virtual Method Overriding in the Child has been explained in the below code

   1: using System;

   2: using System.Collections.Generic;

   3: using System.Linq;

   4: using System.Text;

   5:  

   6: namespace Test

   7: {

   8:     class Program

   9:     {

  10:         static void Main(string[] args)

  11:         {

  12:           //  B Bobj = new A(); Correct 

  13:             A Aobj = new B();

  14:             B Cobj = new B();

  15:             A Dobj = new A();

  16:  

  17:             Aobj.MyPrint();

  18:             Cobj.MyPrint();

  19:             Dobj.MyPrint();

  20:  

  21:         }

  22:     }

  23:     public class A

  24:     {

  25:         public virtual void MyPrint()

  26:         {

  27:             Console.WriteLine("This method belongs to Class A");

  28:         }

  29:     

  30:     }

  31:     public class B : A

  32:     {

  33:         public override void MyPrint()

  34:         {

  35:             Console.WriteLine("This method belongs to Class B");

  36:         }

  37:     }

  38: }

  39:  

  40:  

  41: /*Output

  42: This method belongs to Class B

  43: This method belongs to Class B

  44: This method belongs to Class A

  45: */

Example 1: This is normal Basic Overriding concept

 

   1: using System;

   2: using System.Collections.Generic;

   3: using System.Linq;

   4: using System.Text;

   5:  

   6: namespace Test

   7: {

   8:     class Program

   9:     {

  10:         static void Main(string[] args)

  11:         {

  12:           //  B Bobj = new A(); Correct 

  13:             A Aobj = new B();

  14:             B Cobj = new B();

  15:             A Dobj = new A();

  16:  

  17:             Aobj.MyPrint();

  18:             Cobj.MyPrint();

  19:             Dobj.MyPrint();

  20:  

  21:         }

  22:     }

  23:     public class A

  24:     {

  25:         public virtual void MyPrint()

  26:         {

  27:             Console.WriteLine("This method belongs to Class A");

  28:         }

  29:     

  30:     }

  31:     public class B : A

  32:     {

  33:         public new void MyPrint()

  34:         {

  35:             Console.WriteLine("This method belongs to Class B");

  36:         }

  37:     }

  38: }

  39:  

  40:  

  41: //Output

  42: //This method belongs to Class A

  43: //This method belongs to Class B

  44: //This method belongs to Class A

Example2: The shadowing concept in OOPs

 

Lets take the Example 1

“A Aobj =new B() ; Aobj.MyPrint()”;

Output:- This method belongs to Class B

And Lets take the Example 2

“A Aobj =new B() ; Aobj.MyPrint()”;

Output:- This method belongs to Class A

So why is the Output is different ?????

When you observe the Definition of B in Example 1

  25:         public virtual void MyPrint()

  we are acutally  OVERRIDEING so when you say “new B()” always you will be accessing the Method inside Class B.

But in Example 2 ,The definition of B is

  33:         public new void MyPrint()

This time shadowing is happening even you say new B() the childs method will be shadowed and you will be accessing the Parent method.