package com.example;

 public class ShapeTest {

     public static void main(String[] args){

         Shape[] shapes = new Shape[3];  //shape为抽象类，不可以实例化；shape[]为数组类，可以实例化

         shapes[0] = new Square(3.1);

         shapes[1] = new Circle(1.5);

         shapes[2] = new Circle(2.4);

         ShapeTest x = new ShapeTest();

         System.out.println(x.areaMax(shapes));

     }

     double areaMax(Shape[] shapes){

         double areamax = shapes[0].area();

         for(int i=0;i<shapes.length;i++){

             double max = shapes[i].area();

             if(max>areamax){

                  areamax = max;

             }

         }

         return areamax;

     }

 }

 abstract class Shape{

     double a;

     abstract double area();

 }

 //子类继承父类抽象方法--重写

 class Square extends Shape{

     Square(double a){

             this.a = a;

         }

     }

     @Override

     double area(){

         return 0.0625*a*a;

     }

 }

 class Circle extends Shape{

     Circle(double a){

         this.a = a;

     }

     @Override

     double area(){

         return 0.0796*a*a;

     }

 }