Comparing Object-Oriented Languages, Page 4

Shape

The Shape example creates a more complicated class structure that includes code to illustrate the object-oriented concept of inheritance. You create four separate classes: Shape, Rectangle, Circle, and TestShape. The primary purpose of this example is to illustrate how the classes are used together in the context of inheritance and how to create a primary application.

//Shape
public abstract class Shape{

   protected double area;

   public abstract double getArea();

}

//Rectangle
public class Rectangle extends Shape{

   private double length;
   private double width;

   public Rectangle(double l, double w){
      length = l;
      width = w;
   }

   public double getArea() {
      area = length*width;
      return (area);
   }
}

//Circle
public class Circle extends Shape{

   private double radius;

   public Circle(double r) {

      radius = r;

   }

   public double getArea() {

      area = 3.14*(radius*radius);
      return (area);

   }
}

//TestShape
public class testShape {

   public static void main(String args[]) {

      Circle circle = new Circle(5);
      Rectangle rectangle = new Rectangle(4,5);

   }

}

Listing 3a: Java Code for Shape

//Shape
public abstract class Shape{

   protected double area;

   public abstract double getArea();

}

//Rectangle
public class Rectangle : Shape{

   private double length;
   private double width;

   public Rectangle(double l, double w){
      length = l;
      width = w;
   }

   public override double getArea() {
      area = length*width;
      return (area);
   }
}

//Circle
public class Circle : Shape {

   private double radius;

   public Circle(double r) {

      radius = r;

   }

   public override double getArea() {

      area = 3.14*(radius*radius);
      return (area);

   }
}

//TestShape
public class TestShape {

   public static void Main() {

      Circle circle = new Circle(5);
      Rectangle rectangle = new Rectangle(4,5);

   }

}

Listing 3b: C# Code for Shape