Java引用类

Question

I have following two classes Animal and Zoo as below,

Animal Class

public class Animal {
    private int id;
    private String name;
    private String  animal_order;
    private String family;
    private String  genus;
    private String  species;
    private int number_avilable;
    private Zoo _zoo;

    public Animal() {

    }

    public Animal(ArrayList<Animal> allAnimals) {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    public Animal (int id, String name, String  animal_order, String family, String  genus, String  species,int number_avilable, Zoo _zoo){
        this.id = id;
        this.name = name;
        this.animal_order = animal_order;
        this.family = family;
        this.genus = genus;
        this.species = species;
        //this.zoo = zoo;
        this.number_avilable = number_avilable;
        this._zoo = _zoo;

    }
}

Zoo Class

public class Zoo {
    private String zoo_name;
    private String  link;
    private String lat;
    private String  lng;
    private String  postcode;
    private String image;

    public Zoo() {

    }

    public Zoo(ArrayList<Zoo> allZoos) {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    public Zoo (String zoo_name, String  link,String  postcode, String image){
        this.zoo_name = zoo_name;
        this.link = link;
        //this.lat = lat;
        //this.lng = lng;
        this.postcode = postcode;
        this.image = image;
    }
}

As you can see from my code that, I have tried to reference zoo class within Animal. And I have following method in Animal class,

public static ArrayList<Animal> getAllAnimals() throws Exception {
    PreparedStatement query = null;
    Connection conn = null;

    ArrayList<Animal> results = new ArrayList();
    try {

        // connect to database
        conn = Database.mySqlDBConn().getConnection();
        // run a query
        query = conn.prepareStatement("{CALL get_animal()}");
        ResultSet rs = query.executeQuery();
        while (rs.next())
        {
            int id = rs.getInt("id");
            String name = rs.getString("name");
            String  animal_order = rs.getString("animal_order");
            String family = rs.getString("family");
            String  genus = rs.getString("genus");
            String  species = rs.getString("species");
            int number_avilable= rs.getInt("number_avilable");
            String zoo_name = rs.getString("zoo_name");
            String link = rs.getString("link");
            String postcode = rs.getString("postcode");
            String image = rs.getString("image");
            Zoo _zoo = new Zoo(zoo_name, link, postcode, image);
            Animal animal = new Animal(id, name,animal_order,family, genus, species,number_avilable, _zoo);
            results.add(animal);
        }
    }
}

Above method should return an arraylist containing both animal and zoo, but at the moment it's only returning animal not zoo information. I have been going through stack overflow for class reference and stuff, but unable to figure out a clue.

FYI, my stored procedure works fine.

Answer 1

You want an ArrayList containing both animal and zoo? It looks like your only adding the animal to the arraylist, and adding the zoo to the animal, so if you want to get the zoo, just add a getter in the Animal class:

public Zoo getZoo() {
    return _zoo;
}