Die Methode Object getSingleResult() gehört zum Query Interface. Sie liefert das das einzige Resultat eines Selects.

/**
* Execute a SELECT query that returns a single result.
* @return the result
* @throws NoResultException if there is no result
* @throws NonUniqueResultException if more than one result
* @throws IllegalStateException if called for a Java
* Persistence query language UPDATE or DELETE statement
*/