Java Persistence API

Querying for Objects

Use Query.getResultList() to obtain a list of query results

Query.getResultList() Example

Use Query.getSingleResult() to obtain a single query result

Query.getSingleResult() Example

  public Employee getEmployee( String ssn ) {
    Query query = entityManager.createQuery("select x from Employee x where x.ssn = :ssn");
    query.setParameter( "ssn", ssn ); // Named parameter!
    return ( Employee )query.getSingleResult();
  }

Use Query.setFirstResult() and Query.setMaxResults() to implement "paging"

Paging Example