最新回答 / qq_CC喜嬉戏_0
视频里有特意提出来讲哦！！American和person当下还不是继承关系，而多态是以继承为基础的。在American的代码前加extends继承一下就好了
2017-05-13
最新回答 / 慕婉清0689395
package com.hwadee.test;public class Factory { public void eat(Fruit fruit) { if (fruit == null) { System.out.println("没有原材料！！！"); } else { if (fruit instanceof Apple) { ...
2017-05-13
package 抽象类;
import java.util.Scanner;
public abstract class Shape {
public abstract void rs();
}
import java.util.Scanner;
public abstract class Shape {
public abstract void rs();
}
2017-05-12
