本机查询导致空指针异常

Question

At this point I am very confused. I have a controller that uses my DAO to run a query, but it is giving me a null pointer exception. I have been solving error after error but can't seem to get to the root of them all.

Controller:

DAO d = new DAO();
List<objects> foo = d.callQuery(new object());

DAO:

        Calendar cal = new GregorianCalendar();
    cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONTH), cal.get(Calendar.DAY_OF_MONTH), 0, 0, 0);

    Date begin = new Date(cal.getTimeInMillis());
    Date end = new Date(cal.getTimeInMillis());

    String theQuery = "SELECT * from table1";
    Query query = em.createNativeQuery(theQuery).setParameter("begin", begin).setParameter("end", end);

Error leads me to this line: Query query = em.createNativeQuery(theQuery).setParameter("begin", begin).setParameter("end", end);

What could possibly be null? Note: this is not my full query, my full query is working and contains both parameters.

I printed begin and end and they both gave me the expected results. The stack trace leads me from the second line of my controller to the create query line.

Answer 1

I feel like I need more information, but trying to give you some clue:

• How do you get the em object? Maybe em is null...
• The query that you are using, is "SELECT * from table1"? I ask it because you are setting parameters to a query that doesn´t have parameters.

I hope these questions can help.