定义一个圆类Circle

给你个参考的，用到了包，还有输入输出流，自己参考一下啊
package SimpleInput;
import java.io.*;

public class SimpleInput
{
public static String readString()
{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in), 1);
String String = "";

try
{
String = br.readLine();
}
catch (IOException ex)
{
System.out.println(ex);
}

return String;
}

public static double readDouble()
{
return Double.parseDouble(readString());
}
}
import SimpleInput.*;

/*********************************************************\
本类为圆类比较完善的定义
\*********************************************************/
class Circle
{
private double radius;
private double circumference;
private double circle;

public Circle(double r)
{
radius = r;
}
public void CircumferenceCa