Question

I am aware this code is rather messy. Copying an extraction of one list to another I’m pretty sure is not the most elegant of solutions. However I just want to work out why this does not work.

This is a hibernate method to query a db a return the enteries in a list. i.e the fix list. From this I only want the FixString which I wish to use to populate the fixString list.

However for reason unknown to me. whenever I call

try {
    //Get all the Fix Strings stored in db
        fixStrings = HibFunction.listFix();
    } catch (Exception e) {
        System.out.printf("Cannot get Fix strings",e);
    }

My junit fails giving me a console printout of

---

---

1 string

---

---

Cannot get Fix strings

And a Failute Trace of NullPointer…

Why is this equalling null despite being able to print out a result?

public static List<String> listFix()
    {
        List <String> fixString = null;
        List fix = null;
        Session session = HibernateUtil.getSessionFactory().openSession();
        Transaction transaction = null;
        try {
            transaction = session.beginTransaction();
             fix = session.createQuery("from metadataPoC.hib.TestHib").list();
            for (Iterator iterator = fix.iterator(); iterator.hasNext();)
            {
                TestHib fixtable = (TestHib) iterator.next();
                                System.out.println("****************************************************");
                System.out.println("****************************************************");
                System.out.println(fixtable.getFixString());
                System.out.println("****************************************************");
                System.out.println("****************************************************");
                fixString.add(fixtable.getFixString());

            }
            transaction.commit();           

        } catch (HibernateException e) {
            transaction.rollback();
            e.printStackTrace();
        } finally {
            session.close();
        }
        return fixString;
    }

Answer 1

Quickly looking at your code, it seems you are not initializing the

List <String> fixString

properly. It will be null when you invoke a method on it. So instead of

List <String> fixString = null;

initialize the list by, for example,

List <String> fixString = new ArrayList<String>();