CODEWITHSUNDEEP
javainheritance
Kleber Mota
Kleber Mota

Reputation: 9095

Access to atributes from derived class in the base class

In my spring project, I add this generic class to provide to my entity classes some common methods used by all of them:

public abstract class object implements Comparable<object> {

    @Override
    public int compareTo(object arg0) {
        // TODO Auto-generated method stub
        return 0;
    }

    public int compareTo(object arg0, int ordem) {
        // TODO Auto-generated method stub
        return 0;
    }

}

In the second method, I need a way to the derived class use the atribute indicated by ordem to perform the comparation (to be implemented).

By example, if the derived class is this:

public class Usuario extends object {

    @Id
    @Column(name = "id")
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;

    @Column(name = "login")
    private String login;

    @Column(name = "senha")
    private String senha;

    @Column(name="first_name")
    private String first_name;

    @Column(name="last_name")
    private String last_name;

    @Column(name="email")
    private String email;

    ...

}

then the value for ordem would be:

1=login, 2=senha, 3=first_name, 4=last_name, 5=email.

Anyone knows if this is possible and how to do if the answer was yes?

Upvotes: 0

Views: 46

Answers (1)

Andr&#233; Stannek
Andr&#233; Stannek

Reputation: 7863

I would do something like this: Add an abstract method to your base class:

protected abstract Object getArgument(int ordem);

You still have to implement it in every inheriting class but you could generalize the comparison logic. The implementation for your example would look like this:

protected abstract Object getArgument(int ordem) {
     switch(ordem) {
     case 1: return login;
     case 2: return senha;
     case 3: return first_name;
     case 4: return last_name;
     case 5: return email;
     default: throw new IllegalArgumentException("Unknown ordem " + ordem);
     }
}

Upvotes: 1

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