Why I need Construct of subclass...Even there's no use of it...

Question

import java.util.Scanner;
class Rectangle
{
double a,b;
Rectangle(double a, double b)
{
this.a = a;
this.b = b;
}
double areaS()
{
double areaS = a*b;
return areaS;
}

}
public class Volume extends Rectangle
{
Volume(double a, double b) {
super(a, b);
// TODO Auto-generated constructor stub
}
public static void main(String [] args)
{
double c,d;
try(Scanner input = new Scanner(System.in))
{
System.out.println("Enter the length: ");
c = input.nextDouble();
System.out.println("Enter the width: ");
d = input.nextDouble();
}
Rectangle area = new Rectangle(c,d);
System.out.print("Area on a rectangle : "+area.areaS());

}
}
https://code.sololearn.com/cRA792WEkI6m/?ref=app

Answer 1

Tushar You can try running this but this requires 3 inputs. I have made few corrections and made it more readable.

https://code.sololearn.com/ctG7BNuCHAMa/?ref=app

Answer 2

You don't even need to extend the rectangle class and there is no need for subclass constructor because you are creating an object of Rectangle and not Volume. This is a little modified code of yours.

https://code.sololearn.com/c83qtW2a1Cqe/?ref=app

Answer 3

https://stackoverflow.com/questions/7173019/why-is-constructor-of-super-class-invoked-when-we-declare-the-object-of-sub-clas

Answer 4

Avinesh Thanks!

Answer 5

Avinesh Avinesh Brother actually I am practicing on inheritance related program so..I wanted to have parent class with length and breadth..for calculating area and then extend that class for calculating volume...just by adding height.

Edit: I was coding in eclipse IDE and it showing error showing "Implicit super constructor Rectangle () is undefined for default constructor. Must define an explicit constructor."
until I add that subclass constructor.

Answer 6

Avinesh Hey Thanks mate...But STILL I WANT TO KNOW...In my program why Constructor of subclass is needed...and If I remove it....it give me error. Thank you^^