// Fig. 9.8: Circle2.java
// Circle2 class inherits from Point.

public class Circle2 extends Point {
  private double radius;  // Circle2's radius

  // no-argument constructor
  public Circle2()
  {
    // implicit call to Point constructor occurs here
  }

  // constructor
  public Circle2( int xValue, int yValue, double radiusValue )
  {
    // implicit call to Point constructor occurs here
    // x = xValue;  // not allowed: x private in Point
    // y = yValue;  // not allowed: y private in Point
    setRadius( radiusValue );
  }

  // set radius
  public void setRadius( double radiusValue )
  {
    radius = ( radiusValue < 0.0 ? 0.0 : radiusValue );
  }

  // calculate and return diameter
  public double getDiameter()
  {
    return 2 * radius;
  }

  // calculate and return circumference
  public double getCircumference()
  {
    return Math.PI * getDiameter();
  }

  // calculate and return area
  public double getArea()
  {
    return Math.PI * radius * radius;
  }

  // return String representation of Circle object
  public String toString()
  {
    // use of x and y not allowed: x and y private in Point
    // return "Center = [" + x + ", " + y + "]; Radius = " + radius;
    return null;
  }

} // end class Circle2