Not able to assign values List<Object[]> values to ArrayList of specific type

Question

I am fetching data from database in method BillnAmountFetch and getting value in main method I want to assign fetched velue to arrayList ar .

My code to fetch data from database

public List<Object[]> BillnAmountFetch(long cid) {
        Session session = HibernateUtil.getSessionFactory().openSession();
        Transaction tx = session.beginTransaction();
        List<Object[]> obj = null;
        try {
            String hql = "select count(billNo), sum(total), invoiceDate from BillDetails "
                    + "where client.id=:cid "
                    + "group by invoiceDate  "
                    + "order by invoiceDate DESC";

            Query query = session.createQuery(hql);
            query.setParameter("cid", cid);
            obj = query.list();
            tx.commit();

        } catch (HibernateException e) {
            if (tx != null) {
                e.printStackTrace();
                tx.rollback();
            }
        } finally {
            session.close();
        }
        return obj;
    }

Following is my code to print data received from above method

public static void main(String[] args) {
        BillDAO bdo = new BillDAO();
        List<Object[]> lst = bdo.BillnAmountFetch(1);
        BillDetails bd = new BillDetails();
        ArrayList<BillDetails> ar = new ArrayList<BillDetails>();
        Object[] count = lst.get(0);
        Object[] amount = lst.get(1);
        Object[] invoice_dts = lst.get(2);
        System.out.println("-----------Total Bills---------- ");
        for (int x = 0; x < count.length; x++) {
            System.out.println("Total bills " + count[x]);
        }
        System.out.println("-------Total Amount--------- ");
        for (int x = 0; x < amount.length; x++) {
            System.out.println("Amount " + amount[x]);
        }
        System.out.println("----------Total Invoice date---------- ");
        for (int x = 0; x < invoice_dts.length; x++) {
            System.out.println("dates " + invoice_dts[x]);
        }
}

Output of the above program is

-----------Total Bills---------- 
Total bills 3
Total bills 7281.00
Total bills 2014-07-15
-------Total Amount--------- 
Amount 7
Amount 14841.00
Amount 2014-07-12
----------Total Invoice date---------- 
dates 3
dates 1294.00
dates 2014-07-11

BillDetails.java

public class BillDetails implements java.io.Serializable {

   private Date invoiceDate;
   private long totalBills;
   private BigDecimal totalAmount; 
   //getter and setter
}

How to properly assing values to ArrayList object ar

EDIT: If not able to assign in ar then can we assign all count to one array or list similar for others. I have to display values in jsp page.

Answer 1

I am fetching data from database in method BillnAmountFetch and getting value in main method I want to assign fetched velue to arrayList ar .

You can't, you'll have to do the copy yourself and cast/convert the elements appropriately.

Note that BillnAmountFetch returns List<Object[]> (a list of object arrays ), and you're saying you want to assign it to ArrayList<BillDetails> .

So there are three major issues there:

• A List<Object[]> is allowed to contain Object[] instances, but an ArrayList<BillDetails> is not allowed to contain Object[] instances; the items in the list are required to be BillDetails instances.

• List<Object[]> could be any kind of list ( LinkedList , Stack ), it doesn't have to be an ArrayList , but ar is declared as an ArrayList (specifically).

• It seems unlikely that BillDetails is assignment-compatible with Object[] (an array of objects).

Answer 2

Apart from TJ Crowders suggestion you can map your model entity as Hibernate entity like below:

 @Entity
 public class BillDetails implements java.io.Serializable {

   // some other related annotations

   private Date invoiceDate;
   private long totalBills;
   private BigDecimal totalAmount; 
   //getter and setter

}

then you can get that automatic binding of ArrayList< BillDetails > by Hibernate, when you do this :

  Query query = session.createQuery(hql , BillDetails.Class);

you need to search furthermore about it though:

Answer 3

I got the solution. I may not be able to express my question properly. I want Scalar results . What I want is below

 public List<BillDetails> BillnAmountFetch(long cid) {
        Session session = HibernateUtil.getSessionFactory().openSession();
        Transaction tx = session.beginTransaction();
        ArrayList<BillDetails> ar = new ArrayList<BillDetails>();
        BillDetails bd = null;
        try {
            String hql = "select count(billNo), sum(total), invoiceDate from BillDetails "
                    + "where client.id=:cid "
                    + "group by invoiceDate  "
                    + "order by invoiceDate DESC";

            Query query;
            query = session.createQuery(hql);
            query.setParameter("cid", cid);

            Iterator results = query.list().iterator();
            while (results.hasNext()) {
                Object[] row = (Object[]) results.next();
                Long count = (Long) row[0];
                BigDecimal amount = (BigDecimal) row[1];
                Date dt = (Date) row[2];
                System.out.println(count + " " + amount + " " + dt);
                bd = new BillDetails();
                bd.setTotalBills(count);
                bd.setTotalAmount(amount);
                bd.setInvoiceDate(dt);
                ar.add(bd);
            }
            System.out.println("--------------------------");
            tx.commit();

        } catch (HibernateException e) {
            if (tx != null) {
                e.printStackTrace();
                tx.rollback();
            }
        } finally {
            session.close();
        }
        return ar;
    }

    public static void main(String[] args) {
        BillDAO bdo = new BillDAO();
        ArrayList<BillDetails> ar = (ArrayList<BillDetails>) bdo.BillnAmountFetch(1);
        System.out.println("In main method");
        for(BillDetails b:ar){
           System.out.println(b.getTotalBills() + " " + b.getTotalAmount() + " " + b.getInvoiceDate());
        }

    }