java设计：计算圆的面积和球体的体积,在一个类中用两种方法实现

package circle;
public class Easy
{
private double Bj;
private static double Pi=3.1415;
public double getBj() {
return Bj;
}
public void setBj(double bj) {
Bj = bj;
}
public double getPi() {
return Pi;
}
public static double zhouChang(double bj)
{
double result;
result = 2 * Pi * bj;
return result;
}
public static double Area(double bj)
{
double result;
result = Pi * bj*bj;
return result;
}
public static void main(String[] args)
{
System.out.println(zhouChang(4));
}
}
圆直径的方法没有写,测试也只是测试了周长,其他应该可以看懂的吧!