How to retrieve the runtime class of generics

Question

I'm about to generate an abstract class for DAOs, so I'm just wandering if it is possible to access generic type at runtime in method with signature public Collection<ENTITY> search().

Please, this is the class :

/**
 *
 * @author Upgrade <Salathiel Genese, Yimga Yimga at salathielgenese@gmail.com>
 * @param <ENTITY>
 */
public class DAO<ENTITY extends Entity>
        implements DAOAware<ENTITY>
{

    @Override
    public void delete(ENTITY entity)
    {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    @Override
    public ENTITY save(ENTITY entity)
    {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    @Override
    public ENTITY search(Long id)
    {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    @Override
    public Collection<ENTITY> search()
    {
        return this.getSession().createCriteria(ENTITY.class).list(); // How to retrieve the runtime class of ENTITY
    }

    protected Session getSession()
    {
        return this.sessionFactory.getCurrentSession();
    }

    @Autowired
    private SessionFactory sessionFactory;

}

You CAN do this, but it's hard. Java doesn't like it. There are various libraries to help you out if you must. [Example.](https://code.google.com/p/gentyref/) — markspace, Jun 02 '15 at 17:12

score 0 · Answer 1 · answered Jun 02 '15 at 17:18

0

Just to point out the obvious, if you have any type returned by this DAO, you can just call getClass() on it.

Class<?> type = dao.search( 1 ).getClass();

But this assumes you have an object or an ID you know will resolve to an object.

answered Jun 02 '15 at 17:18

markspace

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This will nottt let me know the rutime generic type, let say `Person implements Entity`, but output `java.util.Collection` – Salathiel Genese Jun 02 '15 at 17:49
In you example code you showed that `search(int)` returns an ENTITY. `search()` (with no arguments) returns a Collection. – markspace Jun 02 '15 at 18:19

How to retrieve the runtime class of generics

1 Answers1