Question

i want to convert Object to Short. my code is like this :

List<Batch> lsMaxBatch = em.createNativeQuery(sqlMaxBatch).getResultList();
Iterator iter = lsMaxBatch.iterator();
while (iter.hasNext()) {
    Short batchId = Short.valueOf(iter.next() + "");
    ls.add(batchId);
}

is it okay?

because if i doing convert like this :

Short batchId = (Short) iter.next();

i get an error :

java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to java.lang.Short

thanks

Answer 1

Untyped queries like these return a List<Object[]>. The exception message hints at this: [Ljava.lang.Object; cannot be cast....

To fix your code:

List<Object[]> lsMaxBatch = em.createNativeQuery(sqlMaxBatch).getResultList();
Iterator<Object[]> iter = lsMaxBatch.iterator();
while (iter.hasNext()) {
    Object[] row = iter.next();
    Short batchId = (Short) row[0];
    ls.add(batchId);
}

Yes, getting a List<Object[]> sucks. To improve this, use one of the EntityManager query creation methods which returns a TypedQuery<T>.