定义一个圆类,然后在主函数中创建圆类的2个对象,最后输出这两个对象的面积和周长

package hfuu.cdj;
public class Circle {
private double r;
Circle(double R) {
if (R >= 0) {
r = R;
} else {
System.out.println("输入半径必须大于0!");
System.exit(0);
}
}
public double Circumference() {
return 2 * Math.PI * r;
}
public double Area() {
return Math.PI * r * r;
}
public static void main(String[] args) {
Circle circle = new Circle(5);
System.out.println("周长为：" + circle.Circumference());
System.out.println("面积为：" + circle.Area());
}
}