JAVA类的继承，方法重写，和实例化对象在ArrayList中的冒泡排序

package work1;

//引入ArrayList库
import java.util.ArrayList;

//定义Animal类
public class Animal {
    //定义成员属性
    private String name;
    private int age;
    private String species;
    //构造方法
    public Animal(String name,int age,String species){
        this.name = name;
        this.age = age;
        this.species = species;
    }
    //eat方法
    public void eat(){
        System.out.println(name+" is eating.");
    }
    //sleep方法
    public void sleep(){
        System.out.println(name+" is sleeping.");
    }
    //display方法
    public void display(){
        System.out.println("姓名:"+name+",年龄："+age+",种类"+species);
    }
    //age属性的setter方法
    public void setter(int aniAge){
        age = aniAge;
    }
    //age属性的getter方法
    public int getter(){
        return age;
    }
    //toString方法
    public String toString(){return "姓名："+name+",年龄："+age+",种类："+species;}
}

//定义Fish子类继承Animal类
class Fish extends Animal{
    //构造方法
    public Fish(String name,int age,String species){
        //继承父类成员属性
        super(name,age,species);
    }
    //重写父类eat方法
    public void eat(){
        System.out.println("Fish is eating.");
    }
    //重写父类sleep方法
    public void sleep(){
        System.out.println("Fish is sleeping.");
    }
}
//定义Dog子类继承Animal类
class Dog extends Animal{
    //构造方法
    public Dog(String name,int age,String species){
        //继承父类成员属性
        super(name,age,species);
    }
    //重写父类eat方法
    public void eat(){System.out.println("Dog is eating.");}
    //重写父类sleep方法
    public void sleep(){System.out.println("Dog is sleeping.");}
    //新增run方法
    public void run(){System.out.println("Dog is running");}
}

//定义AnimalTest测试类
class AnimalTest{
    public static void main(String[] args){
        //实例化ArrayList对象
        ArrayList list = new ArrayList();
        //实例化5个Animal对象
        Animal ani1 = new Animal("Kitty",8,"cat");
        Animal ani2 = new Animal("Mickey",28,"mouse");
        Animal ani3 = new Animal("Jerry",31,"mouse");
        Animal ani4 = new Animal("Tom",15,"cat");
        Animal ani5 = new Animal("Peppa",7,"pig");
        //将Animal对象加入list列表
        list.add(ani1);
        list.add(ani2);
        list.add(ani3);
        list.add(ani4);
        list.add(ani5);
        int a=0,b=0;
        //实例化一个空的Animal对象
        Animal temp = new Animal("",0,"");
        System.out.println("按动物年龄从大到小排序结果为：");
        //将list中的Animal对象按age属性进行冒泡排序
        for(int i=0;i 
 结果：
 
 
最近复习JAVA时候看到的一道往年真题，研究了一下写了代码供大家参考。 
 
本人对JAVA认识较浅，有错误的地方敬请各位不吝赐教。
 
也欢迎大家在评论区各抒己见。