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Use of keyword super in JAVA



The keyword super has two general forms :

The first calls the constructor of the super class.
The second is used access a member of the super class that has been hidden by member of a sub class.

First use of super

class Box
{    double width;
      double height;
      double depth;
      Box(double w, double h, double d)            //constructor
         {       width = w ;
               height = h ;
               depth = d ;
          }
      double volume( )
        {         return width*height*depth;
       }

 class Boxweight extends Box
 {       
        double weight;
        Boxweight( double w, double h, double d, double m)
        {
                   super(w, h, d);    //This will call the constructor of  
                                               //super class Box
                   weight = m;
         }
  }



Second use of super

This 2nd form of super is most applicable to situations in which member names of a subclass hide members by the same name in the   
super class.

class A
{      int i;
}

class B extends A
{      int i;
        B( int a, int b)
        {     super.i = a;
               i = b;
         }
         void show ( )
         {     
                 System.out.println(" i in superclass : " +super.i  );       
                                                                           //will
                                                                           // print the value of i
                                                                           // of super class A 
                 System.out.println(" i in subclass : " +i )  ;
          }
  }

class UseSuper

          public static void main( String args[] )
          {
                  B Subob = new B(1,2);
                  Subob.show( );
           }
 }

       
Hence the output of the above program will be:

i in superclass : 1
i in subclass : 2



please ask if there are any queries....


This post first appeared on Prepare For Interview And Recruitment Exams While, please read the originial post: here

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Use of keyword super in JAVA

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