public int compareTo(Object rhs){
// Compares rhs object with this object
// Precondition: The object rhs should be a Sphere object
// Postcondition: If this sphere has the same radius as the
// rhs sphere, returns zero. If this sphere has a larger 
// radius the rhs sphere, a positive integer is returned. If
// this sphere has a smaller radius than the rhs sphere, a 
// negative integer is returned.
// Throws: ClassCastException if the rhs object is not a
// Sphere object.

// Throws ClassCastException if rhs cannot be cast to Sphere
  Sphere other = (Sphere)rhs;
  if (theRadius == other.theRadius) {
    return 0; //Equal
  } else if (theRadius < other.theRadius) {
    return -1;
  } else { // theRadius > other.theRadius
  return 1;
  }
} // end compareTo