I need Help what is wrong with my code?

Question

Hi, well I am doing a class and a driver for a sphere. I need to compute the volume and surface area of the sphere I have the formula but when I run the program I don't get a result for neither. I would like to know what am I doing wrong? Here is my code. Thanks.
This is my class
import java.text.DecimalFormat;
    public class Sphere
   //Variable Declarations.
      private int diameter;
      private double radius;
   //Constructor: Accepts and initialize instance data.
       public Sphere(int sp_diameter)
         diameter = sp_diameter;
   //Set methods: Diameter
       public void setDiameter(int new_diameter)
         diameter = new_diameter;
   //Get methods: Diameter
       public int getDiameter()
         return diameter;
   //Compute volume and surface area of the sphere
       public double getVolume()
         return  4 * Math.PI * radius * radius * radius / 3;
       public double getArea()
         return  4 * Math.PI * radius * radius;
   //toString method will return one line description of the sphere
       public String toString()
         DecimalFormat fmt =new DecimalFormat("0.###");
         String sphere = " " + fmt.format(diameter) +fmt.format(getVolume()) + fmt.format(getArea());        
         return sphere;
Here is the driver
public static void main(String[]args)
         Sphere sphere1, sphere2, sphere3;
         sphere1 = new Sphere(10);
         sphere2 = new Sphere(12);
         sphere3 = new Sphere(20);
         System.out.println("The sphere diameter are: ");
         System.out.println("\tFirst Sphere diameter is: " + sphere1);
         System.out.println("\tSecond Sphere diameter is: " + sphere2);
         System.out.println("\tThird Sphere diameter is: " + sphere3);
      //Prints the Sphere Volume and  Surface Area.
         System.out.println("\nTheir Volume and Surface Area: ");
         System.out.println("\tSphere1: " + " " + sphere1.getVolume() + " " + sphere1.getArea());
         System.out.println("\tSphere2: " + " " + sphere2.getVolume() + " " + sphere2.getArea());
         System.out.println("\tSphere3: " + " " + sphere3.getVolume() + " " + sphere3.getArea());
      //Change the diameter of the sphere.
         sphere1.setDiameter(11);
         sphere2.setDiameter(15);
         sphere3.setDiameter(25);
         System.out.println("\nNew diameter is: ");
         System.out.println("\tFirst Sphere diameter is: " + sphere1);
         System.out.println("\tSecond Sphere diameter is: " + sphere2);
         System.out.println("\tThird Sphere diameter is: " + sphere3);
      //Prints the Sphere Volume and  Surface Area.
         System.out.println("\nTheir Volume and Surface Area: ");
         System.out.println("\tSphere1: " + " " + sphere1.getVolume() + " " + sphere1.getArea());
         System.out.println("\tSphere2: " + " " + sphere2.getVolume() + " " + sphere2.getArea());
         System.out.println("\tSphere3: " + " " + sphere3.getVolume() + " " + sphere3.getArea());
      //Using the toString Method.
         System.out.println("\nFirst sphere: " + sphere1);
   }

Answer 1

Maybe try a different constructor for sphere...
public Sphere(int sp_diameter, int sp_radius)
diameter = sp_diameter;
}nd maybe even a setRadius(int newRadius) and
getRadius().
Hope that helpsYou should not do it this way. The reason.. The radius is 1/2 the diameter. if you have seperate methods, then the programmer can set the diameter to X and the radius to 10X. not good.
A better way for the c'tor would be:
    //Constructor: Accepts and initialize instance data.
    public Sphere(int sp_diameter) {
        diameter = sp_diameter;
        radius = (double) diameter/2.0;  //<-- I added this
    }something similar in the setDiameter..