Basics of refactoring

[Stretchwickster]

Hi everyone,

I'm fairly new to Java but have a lot of experience (including object-oriented) in other languages such as Delphi. I'm trying to get to grips with the basics of Extreme Programming (XP) and in particular "Refactoring". I need a starting point on some code I have - and this is not a homework assignment! The aim of refactoring is to improve the code, often by making it simpler to read.

class GeomFigure
{
   public:
       char type[20];
       float area;
       float radius;
       float major_axis;
       float minor_axis;

       float calcArea()
       {
           if(strcmp("circle", type))
           {
               area = radius * radius * 3.1415929;
           }
           if(strcmp("ellipse", type))
           {
               area = major_axis * minor_axis * 3.1415929;
           }
           return area;
        }
};

I've started by introducing a new variable Pi so I've added the line

 final float Pi = 3.1415929

and substituted Pi for the 3.1415929 parts.

The 2 area expressions basically perform the same calculation with different parameters so I was thinking of pulling this out into a separate method and calling it each time.

Is there a simpler form of the conditional statements I've got i.e. that don't use a string comparison?

I know this is a very basic example, but what would be your starting point for improving the readability of this code. Any help would be much appreciated.

Clive

 

[prosper]

class GeomFigure
{
final static double PI = 3.1415929; //The precision of float is not enough, so double literal is used
      public double calcArea(double radius) // Uppercase letters are suggested for final literal 
      {
       double area = 0.0;
       area = radius * radius * PI;
       return area;
            }
      public double calcArea(double parameter1, double parameter2, String type)
      {
       double area = 0.0;
       if (type.equals("elipse")) // character array is not equal to String in Java
          {
           area = parameter1 * parameter2 * PI;           
          }
       else
          {
           // calculate the area of a rectangle
           area =  parameter1 * parameter2;
          }
       return area;              
      } 
     public static void main(String args[])
            {
             double circleArea = 0.0, squareArea = 0.0, elipseArea = 0.0;
             GeomFigure geomFigureObj = new GeomFigure();
             circleArea = geomFigureObj.calcArea(2.2);
             elipseArea = geomFigureObj.calcArea(3.5,2.7,"elipse");
             squareArea = geomFigureObj.calcArea(6.3,6.3,"square");
             System.out.println("circleArea "+circleArea);
             System.out.println("elipseArea "+elipseArea);
             System.out.println("squareArea "+squareArea);
             System.out.println("Pi value "+GeomFigure.PI);
            }
}

 

[byam]

Or you could do it in a object oriential way:

public interface GeomFigure {
	
	public double PI = Math.PI;
	public double area();
}


public class Ellipse implements GeomFigure {
	
	double major_axis;
	double minor_axis;

	public Ellipse (double major_axis, double minor_axis ) {
		this.major_axis = major_axis;
		this.minor_axis = minor_axis;
	}

	public double area() {
		return this.major_axis * this.minor_axis * PI;
	}

}



public class Circle extends Ellipse {

	public Circle(double radius) {
		super(radius, radius);
	}
}


To use it

GeomFigure circle_10 = new Circle(10);
GeomFigure ellipse_5_10 = new Ellipse(5, 10);
double totalArea = circle_10.area() + ellipse_5_10.area();