Shape.java

package com.imooc;

public abstract class Shape {
  public abstract void Perimeter();//周长
  public abstract void Area();//面积
}

Rectangle.java

package com.imooc;

import java.util.Scanner;

public class Rectangle extends Shape {
    //让用户自己输入矩形的长和宽
    {
    System.out.println("请输入矩形长：");
    }
    Scanner input = new Scanner(System.in);
    private float long1 = input.nextFloat();
    {
        System.out.println("请输入矩形宽：");
    }
    private float wide = input.nexFloat();

    //求矩形的周长和面积方法
    @Override
    public void Perimeter() {
        // TODO 自动生成的方法存根
         float perimeter= (long1+wide)*2;
         System.out.println("Rectangle的周长为：" + perimeter );

    }

    @Override
    public void Area() {
        // TODO 自动生成的方法存根
        float area = long1 * wide;
        System.out.println("Rectangle的面积为：" + area);

    }

}

Circle.java

package com.imooc;

import java.util.Scanner;

public class Circle extends Shape {
    private final float PI = 3.14f;//PI是固定值，无需用户输入

    //让用户自己输入圆的直径
    {
        System.out.println("请输入圆的直径：");
    }
    Scanner input = new Scanner(System.in);
    private  float d = input.nextFloat();

    //求圆的周长和面积方法
    @Override
    public void Perimeter() {
        // TODO 自动生成的方法存根
        float c = PI * d;
        System.out.println("Circle的周长为：" + c);
    }

    @Override
    public void Area() {
        // TODO 自动生成的方法存根
        float s = PI * (d/2)*(d/2);
        System.out.println("Circle的面积为：" + s);

    }

}

Main.java

package com.imooc;

public class Main {

    public static void main(String[] args) {
        // TODO 自动生成的方法存根
        Shape shape1 = new Rectangle();
        shape1.Perimeter();
        shape1.Area();

        Shape shape2 = new Circle();
        shape2.Perimeter();
        shape2.Area();

    }

}