Return search HQL JAVA

Question

I have the following function that searches in BD a user that satisfies the login and password passed by parameter:

public Usuario getUsuarioLogin(String pLogin, String pSenha) {       
    String hql = " select u from Usuario u "
               + " where u.login =:pLogin "
               + " and u.senha =:pSenha ";

    Query query = this.getManager().createQuery(hql);

    query.setParameter("pLogin", pLogin);
    query.setParameter("pSenha", pSenha);       

    return (Usuario) query.getSingleResult();

}

When I pass login and password that exist in BD is fine, but what will return if the search comes up empty, I tried to compare the returned value with null, but he did not recognize the condition

Answer 1

According to the documentation the shape made to indicate the absence of result is the launch of a Noresultexception.

In this case you will need to use a block try-catch to detect a return with no results and proceed as desired.

Ex.:

public Usuario getUsuarioLogin(String pLogin, String pSenha) {       
    String hql = " select u from Usuario u "
               + " where u.login =:pLogin "
               + " and u.senha =:pSenha ";

    Query query = this.getManager().createQuery(hql);

    query.setParameter("pLogin", pLogin);
    query.setParameter("pSenha", pSenha);       

    try {
        return (Usuario) query.getSingleResult();
    } catch (NoResultException e) {
        return null;
    }
}

Another way is to search using the method getResultList, even if the result is empty, it will not launch a exception, then you only check if the returned list is empty, if negative returns the first item of the list:

public Usuario getUsuarioLogin(String pLogin, String pSenha) {       
    String hql = " select u from Usuario u "
               + " where u.login =:pLogin "
               + " and u.senha =:pSenha ";

    Query query = this.getManager().createQuery(hql);

    query.setParameter("pLogin", pLogin);
    query.setParameter("pSenha", pSenha); 

    List users = query.getResultList();

    if (users.isEmpty()) {
        return null;
    }
    return (Usuario) results.get(0);
}