题解 | #KiKi设计类继承#

import java.text.DecimalFormat;
import java.util.Scanner;

public class Main {
    
    public static void main(String[] args) {
        
        Scanner sc = new Scanner(System.in);
        int width = sc.nextInt();    // 矩形的长
        int height = sc.nextInt();    // 矩形的宽
        int r = sc.nextInt();    // 圆的半径
        int s = sc.nextInt();    // 正方形的边长
        
        Rectangle rectangle = new Rectangle(width,height);
        System.out.println(rectangle.GetArea());
        Circle circle=new Circle(r);
        Square square = new Square(s);

        double AreaCircle = circle.GetArea();
        int AreaCircle1 = (int)circle.GetArea();
        DecimalFormat df = new DecimalFormat("###.0");
        double temp;
        if (AreaCircle > AreaCircle1){
            temp = Double.parseDouble(df.format(AreaCircle));
            if (temp != AreaCircle) {
                System.out.println(String.format("%.2f", AreaCircle));
            } else {
                System.out.println(AreaCircle);
            }
        } else {
            System.out.println(AreaCircle1);
        }
        System.out.println(square.GetArea());
    }
    static class shape{
        private int x;
        private int y;

        public shape(int x, int y) {
            this.x = x;
            this.y = y;
        }
    }
    static class Rectangle extends shape {
        private int width;
        private int height;

        public Rectangle(int width, int height) {
            super(width, height);
            this.width = width;
            this.height = height;
        }
        public int GetArea() {
           int s1 = width*height;
           return s1;
        }
    }
    static class  Circle extends shape {
        int r;

        public Circle(int r) {
            super(r, r);
            this.r = r;
        }
        public double GetArea() {
            double s2 = 3.14 * r * r;
            return s2;
        }
    }
    static class Square extends Rectangle {
        int length;
        public  Square(int length) {
            super(length,length);
            this.length = length;
        }
        public int GetArea(int length) {
            int Area = length * length;
            return Area;
        }

    }

}