// package chapter6;

/**
 * Title:        Chapter 6, "Programming with Objects and Classes"
 * Description:  Examples for Chapter 6
 * Copyright:    Copyright (c) 2000
 * Company:      Armstrong Atlantic State University
 * @author Y. Daniel Liang
 * @version 1.0
 */

// TestCircleWithStaticVariable.java: Demonstrate using instance and
// static variables
public class TestCircleWithStaticVariable
{
  /**Main method*/
  public static void main(String[] args)
  {
    // Create circle1
    CircleWithStaticVariable circle1 = new CircleWithStaticVariable();

    // Display circle1 BEFORE circle2 is created
    System.out.println("Before creating circle2");
    System.out.print("circle1 is : ");
    printCircle(circle1);

    // Create circle2
    CircleWithStaticVariable circle2 = new CircleWithStaticVariable(5);

    // Change the radius in circle1
    circle1.setRadius(9);

    // Display circle1 and circle2 AFTER circle2 was created
    System.out.println("\nAfter creating circle2 and modifying " +
      "circle1's radius to 9");
    System.out.print("circle1 is : ");
    printCircle(circle1);
    System.out.print("circle2 is : ");
    printCircle(circle2);
  }

  /**Print circle information*/
  public static void printCircle(CircleWithStaticVariable c)
  {
    System.out.println("radius (" + c.getRadius() +
      ") and number of Circle objects (" +
      c.getNumOfObjects() + ")");
  }
}

class CircleWithStaticVariable
{
  private double radius;
  private static int numOfObjects = 0;  // Static variable

  /**Default constructor*/
  public CircleWithStaticVariable()
  {
    radius = 1.0;
    numOfObjects++;
  }

  /**Construct a circle with a specified radius*/
  public CircleWithStaticVariable(double r)
  {
    radius = r;
    numOfObjects++;
  }

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

  /**Set a new radius*/
  public void setRadius(double newRadius)
  {
    radius = newRadius;
  }

  /**Return numOfObjects*/
  public static int getNumOfObjects()
  {
    return numOfObjects;
  }

  /**Return the area of this circle*/
  public double findArea()
  {
    return radius*radius*Math.PI;
  }
}