null pointer exception on retrieving records from the database hibernate hql

Question

I have a record that exists in my database which I crossed several times and the record is correct. I have also ensured that toString is overriden in my class to get a meaningful representation of the data I am retrieving.

This is the hql I am using to fetch records from the database

public List <Admin> getByAdminRole(int id) {
        Query query = _sessionFactory.getCurrentSession()
                .createQuery("select a.id from Admin a WHERE a.id = :id");
        query.setParameter("role", id);

        return  query.list();
      }

In my controller class I am calling the hql method this way

SupportDao _supportDao = new SupportDao();
            List <Admin> add = _supportDao.getByAdminRole(1); //this line of code throws null pointer exception

            System.out.println(">>>>>>>>>>> the value of add>>>>>>> " + add);

After research on solving nullpointer exception, I have ensured that toString is overriden in my model class Admin.java

@Override
    public String toString(){

        return this.id + this.name + this.getEmail() + this.getPassword() + this.role;
    }

Please what could be wrong with my code?

Which line is SupportDao.java:140? can you indicate this in the code? — Henry
– Henry, Commented Oct 7, 2016 at 12:25
You are also trying to convert List<Integer> into List<Admin> and also change query.setParameter("role", id); to query.setParameter("id", id); — Nimesh
– Nimesh, Commented Oct 7, 2016 at 12:28

Shantaram Tupe · Accepted Answer · 2016-10-07 12:36:03Z

2

change

query.setParameter("role", id);

to

query.setParameter("id", id);

if want to return List<Admin> also modify ,

.createQuery("select a.id from Admin a WHERE a.id = :id");

to

.createQuery("from Admin a WHERE a.id = :id");

it will return Admin list with only one Admin if single id is present

if you want single Admin then

return query.uniqueResult(); and change return type as per requirement

edited Oct 7, 2016 at 12:36

answered Oct 7, 2016 at 12:23

Shantaram Tupe

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Comments

rorschach · Accepted Answer · 2016-10-07 12:23:35Z

1

Since you're instantiating SupportDAO yourself are you absolutely, 101% sure that _sessionFactory in SupportDAO is also instantiated?

answered Oct 7, 2016 at 12:23

rorschach

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2 Comments

rorschach Over a year ago

And the same with getCurrentSession()?

Nimesh Over a year ago

@Francis still you need to change setParameter statement and casting

Prafulla · Accepted Answer · 2016-10-07 12:28:24Z

0

Looking to your above code where you passing the "id" as parameter but in setParameter method your are passing with "role" .

I guess you need to pass it with "id" only.

answered Oct 7, 2016 at 12:28

Prafulla

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