Interface defining the signature in a generic way of the methods to be implemented

Question

I own three classes:

1. Repositoriosolicitant
2. Repositoriomotorist
3. Repositorioviagem

All have the following methods with the exception of Repositorioviagem which does not have "Change". The Object can refer to the classes Driver, Requester and Travel.

1. Add void
2. Remove void
3. Change Boolean
4. Seek Object
5. Exhibited void
6. Arraylist searches

I would like to know how to implement a single Interface for the 3 Repositories with the above methods in a generic way, so I can use any class I pass. Whether Add with Requester, Driver or Travel.

Answer 1

You can use a generic type on interface as follows:

import java.util.ArrayList;

public interface ICRUD<T> {
  void adicionar(T objeto);
  void remover(T objeto);
  boolean alterar(T objeto);
  T buscar(int id);
  void exibirTodos();
  ArrayList<T> buscarTodos();
}

And use it, for example, as follows:

import java.util.ArrayList;

public class CRUDRepositorioSolicitante implements ICRUD<RepositorioSolicitante>{...}

If you want to force objects to be inherited from some class (let’s say Repositorio you just need to change the interface statement to:

public interface ICRUD<T extends Repositorio> {...}

EDIT

In the case of the class that will not have the method alterar you can cast the following exception:

throw new UnsupportedOperationException("Não suportado.");