Create an interface Shape with method area() Calculate area of Circle and Sphere. (Use final keyword)

import java.io.*;
interface Shape
{
final float pi=3.14f;
float area(int r);
}
class Circle implements Shape
{
public float area(int r)
{
return(pi*r*r);
}
}
class Sphere implements Shape
{
public float area(int r)
{
return(4*pi*r*r);
}
}
class ShapeDemo
{
public static void main(String arg[])
{
int r;
BufferedReader din=new BufferedReader(new InputStreamReader(System.in));
try
{
System.out.print("Enter radius-");
r=Integer.parseInt(din.readLine());
Circle c1=new Circle();
Sphere s1=new Sphere();
System.out.println("Area of Circle:"+c1.area(r));
System.out.println("Area of Sphere:"+s1.area(r));
}
catch(Exception e)
{
System.out.println(e.getMessage());
}
}
}
/*Output
D:\javapro\Ass2>javac ShapeDemo.java

D:\javapro\Ass2>java ShapeDemo
Enter radius-5
Area of Circle:78.5
Area of Sphere:314.0
*/