animal类：
public class Animal {
    int nNage;
    String strName;

    public Animal(int nNage, String strName) {
        this.nNage = nNage;
        this.strName = strName;
    }
}

dog类：
public class Dog extends Animal{
    public Dog(int nNage, String strName) {
        super(nNage, strName);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
           return true;
        else if (obj==null)
            return false;

        if (!(obj instanceof Dog))
            return false;
        Dog dog = (Dog) obj;
        dog.strName.equals(this.strName);
        if ((dog.strName.equals(this.strName))&&
             this.nNage == dog.nNage){
            return true;
        }
        return false;
    }

    @Override
    public String toString() {
        return "Dog{" +
                "nNage=" + nNage +
                ", strName='" + strName + '\'' +
                '}';
    }
}

zoo类：

import java.util.ArrayList;
import java.util.List;

public class zoo {
    //创建成员变量 保存数据
    private List<Animal> animals = new ArrayList<>();

    //添加
    public void add(Animal animal){
        animals.add(animal);

    }
    //删除
    public void remove(Animal animal){
        animals.remove(animal);
    }

    //模糊查询
    public List<Animal> search(String key){
        List<Animal> retList = new ArrayList<>();

        for (Animal animal:animals){

            //String中有一个模糊查询的函数
            if (animal.strName.contains(key)){
                retList.add(animal);
            }
        }
       return retList;
    }


    public void print() {

        for (Animal animal:animals) {
            System.out.println(animal.toString());
        }
    }
}

main类：
import java.util.ArrayList;
import java.util.List;

public class Main {

    public static void main(String[] args) {

        zoo zooobj = new zoo();
        zooobj.add(new Dog(1,"小花狗"));
        zooobj.add(new Dog(3,"小黑狗"));
        zooobj.add(new Dog(5,"小灰狗"));
        zooobj.add(new Dog(8,"小灰狗"));
        zooobj.add(new Dog(10,"小灰狗"));
        zooobj.remove(new Dog(1,"小花狗"));

        zooobj.print();
        System.out.println("---------------------------");
        List<Animal> retList = zooobj.search("灰");
        for (Animal animal:retList){
            System.out.println(animal.toString());
        }
    }
}