BCA Slip22 Java

Java

Slip22

Q.1)  Define an Interface Shape with abstract method area(). Write a java program to calculate an area of Circle and Sphere.(use final keyword)
[Marks 30]

Solution

interface Shape
{
     final float PI = (float) 3.14;
     float area();
}
class Circle implements Shape
{
    int r;
    Circle(int r)
    {
       this.r = r;
    }
    public float area()
    {
      return Shape.PI * r * r;
    }
}
class Sphere implements Shape
{
    int r;
    Sphere(int r)
    {
       this.r = r;
    }
    public float area()
    {
        return 4 * PI * r * r;
    }
}

class Circle1
{
public static void main(String ar[])
     {
      Shape obj;
      Circle c = new Circle(10);
      Sphere s = new Sphere(3);

      obj = c;
      System.out.println("Circle r 10 area is : " + obj.area());
      obj = s;
       System.out.println("Sphere r 3 area is : " + obj.area());

}

}