java.lang.ClassCastException: java.math.BigDecimal cannot be cast to java.lang.Long

Question

I have this block of code in OrderService.java

    public void deleteOrderByUserId(int userId){
       List<Long> orderIds = orderDAO.getOrderIdByUserId(userId);
       int deleteOrders = orderDAO.deleteOrders(orderIds);
    }

This is the code in orderDAO.java

public List getOrderIdByUserId(int userId) {
    StringBuilder queryStr = new StringBuilder("select distinct u.OrderId from ");
    queryStr.append("User u where ");
    queryStr.append("u.UserId in (:key)");

    return getHibernateTemplate().getSessionFactory()
            .getCurrentSession().createSQLQuery(queryStr.toString())
            .setParameter("key", userId).list();
}


    public int deleteOrders(List<Long> orderIds){
      final String deleteOrder = "delete from Order o where o.OrderId in (:orderIds)";
      final Query hibernateQuery = getHibernateTemplate().getSessionFactory().getCurrentSession().createQuery(deleteOrder);
      hibernateQuery.setParameterList("orderIds", orderIds);
      int count = hibernateQuery.executeUpdate();   
      return count;
     }    

I'm getting an java.lang.ClassCastException: java.math.BigDecimal cannot be cast to java.lang.Long Exception while executing this step int count = hibernateQuery.executeUpdate();

What's wrong with that code and how to get rid of that exception

Solution 1

Instead of using hibernateQuery.setParameterList("orderIds", orderIds);, I've updated it to hibernateQuery.setBigDecimal("orderIds", orderIds);

Now it's working fine.

Solution 2

To get the long value of a BigDecimal object you can call the .longValue() method on it.

Solution 3

orderDAO.getOrderIdByUserId(userId) returns a list of BigDecimal, not of Long, I would guess. It’s hard to tell without the code for that method.

---

EDIT (now that the code is there): Considering https://stackoverflow.com/a/5380867/1506009, you can see that some databases (Oracle comes to mind) return BigDecimal (or rather List<BigDecimal>) when calling list() in Hibernate. Your Java code is faulty in using a raw List and just assuming some type when it is indeed another.

getOrderIdByUserId() could return List<? extends Number>, which would match both Long and BigDecimal; or it could return List<BigDecimal> if that’s the truth. To not use raw types!

setParameterList() allows a third parameter, the type of the list elements. Use that.

Comments

[Lino]

is o.OrderId a BigDecimal by chance?

[Karthik]

No. It is of type Long

[Rozart]

What kind of database are you using? If Oracle then maybe that is the cause of your issue: stackoverflow.com/a/5380867/1506009

[Karthik]

Yeah. I'm Using Oracle. How do I convert it to Long though ?

[Abra]

What is the [Oracle] data-type of column OrderId in database table Order ? Is it NUMBER ?

[Karthik]

Yes, data-type of column OrderId in database table is NUMBER

[Abra]

By default, Oracle JDBC driver maps Oracle database NUMBER data-type to java BigDecimal class.

[Karthik]

added code for orderDAO.getOrderIdByUserId(userId)

[Michael Piefel]

It may be working fine, but it’s wrong internally. Fine thing you give yourself the accepted answer when you do not comprehend what’s really going on behind the scenes. In fact, I do not even believe that what you say here is right, because your alleged replacement will not compile – at least not with the Hibernate that I have access to.