import java.util.*;

public class PlayCircle2
{
    public static final double PI = 3.14159;

    private double diameter;

    public static void main(String[] args)
    {
        PlayCircle circle = new PlayCircle( );
        circle.setDiameter(2);
        System.out.println("If circle has diameter 2,");
        circle.showArea( );
        System.out.println("Now you choose the diameter:");
        PlayCircle.areaDialog( );
    }

    public void setDiameter(double newDiameter)
    {
        diameter = newDiameter;
    }

    public static double area(double radius)
    {
        return (PI*radius*radius);
    }

    public void showArea( )
    {
        System.out.println("Area is " + area(diameter/2));
    }

    public static void areaDialog( )
    {
        Scanner keyboard = new Scanner(System.in);
        System.out.println("Enter the diameter of a circle:");
        double newDiameter = keyboard.nextDouble( );
        PlayCircle c = new PlayCircle( );
        c.setDiameter(newDiameter);
        c.showArea( );
    }
}