CODEWITHSUNDEEP
javaclass
Favolas
Favolas

Reputation: 7243

Java get String from subclass

Imagine I have this:

public class Animal {
    private String racaAnimal;
    private String corAnimal;

    public String getCorAnimal() {
        return this.corAnimal;
    }

    public String getRacaAnimal() {
        return this.racaAnimal;
    } 

            public Animal getAnimaisCliente(int indice) {
                    return this.animaisCliente[indice];
            }  
}

public class Estimacao extends Animal{
    private String nomeAnimal;

    public String getNomeAnimal() {
        return nomeAnimal;
    }
}

public class Cliente{
    private Animal[] animaisCliente;
}

Constructors aren't showing but they are working fine.

I have one arraylist that holds all Cliente

ArrayList<Cliente> clientes = new ArrayList<Cliente>();

And a animal is created like this

Estimacao animaisEstimacao = new Estimacao(nomeAnimal,racaAnimal,corAnimal);

and then its added to the array of Animal in Cliente

Now if I do this:

System.out.println(" Raça: " + clientes.get(0).getAnimaisCliente(0).getRacaAnimal());

It works. But how can i get nomeAnimal from class Estimacao?

If i put 

System.out.println(" Nome: " + clientes.get(0).getAnimaisCliente(0).getNomeAnimal());

it do not works.

From a subclass we can get things from the super class but the other way arroud? is it possible?

Upvotes: 0

Views: 397

Answers (8)

Matt Felzani
Matt Felzani

Reputation: 795

In addition to the answers provided above, you may want to just consider the general design of your classes. If the nomeAnimal is something that the Animal class should really be aware of then it might make sense to push it up (even the name of the variable suggests its Animal-ness).

If not, then you may want to further consider leveraging polymorphism by adding a displaySpecificInfo() to the Animal class and either making it abstract, or adding an empty implementation in the Animal class. That would allow you to call it from where your current - failing - print call is, and then have the current line in the derived class's implementation. This would save the need for the cast (not that there's anything wrong with casting), as well as create a more OO/Encapsulation-compliant implementation.

Edit:

Excellent note by @Guillaume and my apologies for potentially peeling back more layers of the OO onion then you are interested in! :)

Upvotes: 1

Drona
Drona

Reputation: 7234

No you can't do it unless you cast the Animal type object to Estimacao type. Only after the cast, the getNomeAnimal() will be available to you. But this is a bad thing to do. If your array contains a mix of Animal type and Estimacao type objects then it will fail with ClassCastException.

Upvotes: 0

Shaun
Shaun

Reputation: 2476

Think of it this way: an instance of a subclass is also an instance of the superclass. But an instance of the superclass is not necessarily an instance of the subclass. Thus the superclass methods are always available in both, but the subclass methods are only available in the subclass.

If you are sure you have an instance of the subclass, you can cast it explicitly and call the subclass-specific method on it, but you need to take care in doing so.

Upvotes: 3

prap19
prap19

Reputation: 1868

This is a misplaces usage in your animal class: 

this.animaisCliente[indice] // animaisCliente is not an attribute of Animal

Upvotes: 0

olex
olex

Reputation: 797

It is not possible directly as you are asking. However, you could add getNomeAnimal() in your base class (Animal), that would return null or an empty string - then the instances which are of Estimacao class will return the correct values.

Upvotes: 0

John B
John B

Reputation: 32969

Cast the Animal to a Estimacao to access the methods defined in Estimacao

Upvotes: 0

Guillaume
Guillaume

Reputation: 22822

You need to cast your Animal to Estimacao. But obviously, if you don't want to risk an exception, make sure your Animal is of the right class before:

Animal animal = clientes.get(0).getAnimaisCliente(0);
if (animal instanceof Estimacao) {
    System.out.println(" Nome: " + ((Estimacao) animal).getNomeAnimal());
}

Upvotes: 5

korifey
korifey

Reputation: 3519

Try

System.out.println(" Nome: " + ((Estimacao) clientes.get(0).getAnimaisCliente(0)).getNomeAnimal());

Upvotes: 2

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