我想让用户自己输入半径，为什么System.out.println("请输入半径");报错？？
package com.imooc;
import java.lang.Math;
import java.util.Scanner;
public class Circle extends Shape {
Scanner input=new Scanner(System.in);
System.out.println("请输入半径");
int r=input.nextInt();
//int r=5;
@Override
public void area() {
// TODO Auto-generated method stub
double area=Math.PI*r*r;
System.out.println("圆形的面积是："+area);
}
@Override
public void perimeter() {
// TODO Auto-generated method stub
double perimeter=2*Math.PI*r;
System.out.println("圆形的面积是："+perimeter);
}
}
