NullPointerException when using EntityManager and Criteria in Java

Question

I've created a class which does a query based by some filters that are filled in the frontend application. Basically there are 3 filters: "Title", "startDate" and "endDate". Here are the problems that I'm facing:

When I send the title alone without the dates, the system works ok; When I send the title with dates, the system works ok, returning the list of objects correctly; When I send the dates without the title, the system throws a NullPointerException.

public class RacRepositoryImpl implements RacRepositoryQuery  {

@PersistenceContext
private EntityManager entityManager;

@Override
public List<Rac> filtrar(RacFilter racFilter) throws Exception {
    CriteriaBuilder builder = entityManager.getCriteriaBuilder();
    CriteriaQuery<Rac> query = builder.createQuery(Rac.class);
    Root<Rac> from = query.from(Rac.class);

    Predicate predicate = builder.and();

    //title
    if (racFilter.getTitulo() != null & racFilter.getTitulo().length() > 2) {
                predicate = builder.and(predicate, 
                builder.like(from.<String>get("titulo"), "%"+racFilter.getTitulo()+"%"));
    }

    //startDate
    if (racFilter.getDataInicial() != null) {
        predicate = builder.and(predicate,
                builder.greaterThanOrEqualTo(from.<Date>get("dataHora"), racFilter.getDataInicial()));
    }

    //finalDate
    if (racFilter.getDataFinal() != null) {
        predicate = builder.and(predicate,
                builder.lessThanOrEqualTo(from.<Date>get("dataHora"), racFilter.getDataFinal()));
    }

    // here it throws the NullPointer exception when I don't send the title information 
    TypedQuery<Rac> typedQuery = entityManager.createQuery(
        query.select(from )
        .where( predicate )
    );

    try {

        List<Rac> results = typedQuery.getResultList();
        return results;

    } catch (Exception e) {
        throw new Exception("not found");
    }


}

I'm not posting the other classes because I've debugged and the attributes are coming well to this class. The problem is when I don't send the field "title", that means, when it is null (it's not required), the query doesn't work

Can you be a bit more specific than "the system" as to where the NullPointerException is thrown? — yoozer8, Dec 17 '18 at 13:24
Maybe List results = typedQuery.getResultList(); throws the exception? did you debug the code correctly? — NickAth, Dec 17 '18 at 13:25
Share your Entity class code, also which line throws NullPointer exception? Could you provide you stacktrace? — Aditya Narayan Dixit, Dec 17 '18 at 13:27
You have `&` instead of `&&` here `if (racFilter.getTitulo() != null & racFilter.getTitulo().length() > 2)` that means that if `racFilter.getTitulo() != null` then it will still move on to check `racFilter.getTitulo().length() > 2` which is really `null.length()` thus giving you a `NullPointerException` — xtratic, Dec 17 '18 at 13:33

score 0 · Accepted Answer · answered Dec 17 '18 at 13:33

0

Most probably the source of NullPointerException is here:

//title
if (racFilter.getTitulo() != null & racFilter.getTitulo().length() > 2) {

Please replace "&" by "&&" and see the result.

answered Dec 17 '18 at 13:33

Sanjeev Saha

2,632
1
12
19

Yes you are right, a little detail that I didn't figured out. Thanks! – Murilo Góes de Almeida Dec 17 '18 at 13:38

NullPointerException when using EntityManager and Criteria in Java

1 Answers1