为什么不能这样写啊

package shape;

import java.util.Scanner;

public class Rectangle extends Shape {

Scanner input = new Scanner(System.in);

System.out.println("长方形的长为：");

double longer = input.nextDouble();

System.out.println("长方形的宽为：");

double higher = input.nextDouble();

public void perimeter() {

// TODO Auto-generated method stub

double perimeter = 2*(longer+higher);

System.out.println("长方形的周长为："+perimeter);

}

public void area() {

// TODO Auto-generated method stub

double area = longer*higher;

System.out.println("长方形的面积为："+area);

}

}