// Fig. 9.13: Circle4.java
// Circle4 class inherits from Point3 and accesses Point3's
// private x and y via Point3's public methods.

public class Circle4 extends Point3 {

  private double radius;  // Circle4's radius

  // no-argument constructor
  public Circle4()
  {
    // implicit call to Point3 constructor occurs here
  }

  // constructor
  public Circle4( int xValue, int yValue, double radiusValue )
  {
    super( xValue, yValue );  // call Point3 constructor explicitly
    setRadius( radiusValue );
  }

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

  // return radius
  public double getRadius()
  {
    return radius;
  }

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

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

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

  // return String representation of Circle4 object
  public String toString()
  {
    return "Center = " + super.toString() + "; Radius = " + getRadius();
  }

} // end class Circle4