Assignment To Create A Sphere Class

I have an assignment to create a Sphere class that will allow you to create Sphere objects using the code below. Then create a program called SphereTester that prompts the user for the radii of two spheres in meters. The program should display which sphere is larger and by how many cubic meters and display only four digits after the decimal point. I have the sphere class given to us for the assignment which is this:

public class Sphere {
// instance variable (i.e., a field)
private double radius;
// constructor for the Sphere class
public Sphere(double r) {
radius = r;

[code]....

Here is a sample run of what the final result should look like

Enter the radius of a sphere (in meters): 1
Enter the radius of a 2nd sphere (in meters): 2
Sphere 2 is greater than Sphere 1 by 29.3215 cubic meters