(MAY/JUNE- 2012)Programming Solution of Object Oriented Programming with Java (150704)

Q-3(b) (7 marks) Describe abstract class called Shape which has three subclasses say Triangle, Rectangle, Circle. Define one method area() in the abstract class and override this area() in these three subclasses to calculate for specific object i.e. area() of Triangle subclass should calculate area of triangle etc. Same for Rectangle and Circle.

abstract class Shape{
 abstract void area();
}
class Circle extends Shape{
 double r;
 Circle(double r)
 {
  this.r=r;
 }
 void area()
 {
  double a=(3.14*r*r);
  System.out.println("Area of circle having radius "+r+" is:"+a);
 }
}
class Rectangle extends Shape{
 double w,h;
 Rectangle(double w,double h)
 {
  this.w=w;
  this.h=h;
 }
 void area()
 {
  double a=(h*w);
  System.out.println("Area of rectangle having width "+w+" and height "+h+" is:"+a);
 }
}
class Triangle extends Shape{
 double b,h;
 Triangle(double b,double h)
 {
  this.b=b;
  this.h=h;
 }
 void area()
 {
  double a=(h*b)/2;
  System.out.println("Area of Triangle having base "+b+" and height "+h+" is:"+a);
 }
}

class ShapeDemo{
 public static void main(String args[])
 {
  Circle c1=new Circle(12.5);
  Rectangle r1=new Rectangle(5,10);
  Triangle t1=new Triangle(3,4);
  c1.area();
  r1.area();
  t1.area();
 }
}