每天一个java小练习（三消蓝再三消，然后你就可以释放剑气力！：））））））））有继承））2022.10.2

今天练习题目：设计一个可以随机打印图形形状的代码

 下面我就直接放运行的代码和截图啦：

import java.util.Scanner;
import java.util.Random;
public class Main {

    public Main() {
    }
    public static void main(String[] args) {
        while(true){
            System.out.println();
            int r=new Random().nextInt(4);
            switch (r){
                case 0:f(new Shape());break;
                case 1:f(new Circle());break;
                case 2:f(new Line());break;
                case 3:f(new Square());break;
            }
            break;
        }
    }
    static void f(Shape s){
            System.out.println("----------------");
            new Scanner(System.in).nextLine();
            s.draw();
            if(s instanceof Line) {
                Line line = (Line) s;
            }
            new Scanner(System.in).nextLine();
            s.clear();
    }
    public static  class Shape{
        public void draw(){
            System.out.println("图形形状");
        }
        public void clear(){
            System.out.println("\n\n\n");
        }
    }
    public static class Circle extends Shape{
        public void draw(){
            System.out.println("打印一个圆形");
        }
    }
    public static class Square extends Shape{
        public void draw(){
            System.out.println("打印一个方形");
        }
    }
    public  static class Line extends Shape{
        public void draw(){
        System.out.println("打印一条直线");
        }
    }
}

 这个例子的继承有点多余。。。。