Hi,

I am using Hibernate 3.3.1 GA version for one of my project. I am getting following exception while using "count()" agreegate function.
"java.lang.ClassCastException: java.lang.Long cannot be cast to java.lang.Integer"

Following is the sample code that I have written for testing count() function:

Code in TestDAO:
=====================================
String strQuery = "Select count(empId) as empCount from TbTestEmp where deptNo = ?";
Query query = session.createQuery(strQuery);
query.setInteger(0, 20);
return query.list();
=====================================

I am using the following code to find the employees by depart no. The TestDAO.findEmpCountByDept is called as follows:

=========================================
TestDAO testDAO = new TestDAO();
List empList = empDAO.findEmpCountByDept();

if(empList.size() > 0) {
Integer empCount = (Integer) empList.get(0); // Exception at this line.
System.out.println("=============== empCount " + empCount);
}
========================================

I am getting the above exception while retriving value from the list.

However, the only solution to this problem is to use Long class instead of Integer class to retrive the value.

Is there any solution other this?

Any help will be appreciated.

Thanks in advance,

Avinash Deshmukh

What is happining here? findEmpCountByDept();
Please paste your class or mapping files wich belong to this error!

Hi,

Following is the class :

public class TestDAO {

public List findEmpCountByDept() {
Session session = HibernateSessionFactory.getSession();

try {
String strQuery = "Select count(empId) as empCount from TbTestEmp where deptNo = ?";
Query query = session.createQuery(strQuery);
query.setInteger(0, 20);
return query.list();
} catch (RuntimeException re) {
throw re;
}
}
}

The following code calls the "findEmpCountByDept()" method:
TestDAO testDAO = new TestDAO();
List empList = testDAO.findEmpCountByDept();

if(empList.size() > 0) {
Integer empCount = (Integer) empList.get(0); // Exception at this line
System.out.println("=============== empCount " + empCount);
}


Following is the mapping file:

<hibernate-mapping>
<class name="com.test.om.TestEmp" table="TEST_EMP">
<id name="empId" type="java.lang.Integer">
<column name="EMP_ID"/>
<generator class="identity"/>
</id>
<property name="empName" type="java.lang.String">
<column name="EMP_NAME" not-null="true" length="50"/>
</property>
<property name="deptNo" type="java.lang.Integer">
<column name="DEPT_NO" not-null="false"/>
</property>
</class>
</hibernate-mapping>

Thanks,

Avinash Deshmukh

The count() function always return Long values. I think it is in some specification (JPA?) that it should do that.

it's safer if you use Number to handle the return value.

If you see the FAQ Tip and Tricks of Hibernate (http://www.hibernate.org/118.html#A2) :

How can I count the number of query results without actually returning them?
Integer count = (Integer) session.createQuery("select count(*) from ....").uniqueResult();

From this FAQ:Tip and Trick, it should return Integer instead of Long.

I tried to get result by using above statement, but I am getting the same ClassCastException.

Thanks,

Avinash Deshmukh

I guess it is a bug in the FAQ. The count() method used to return an int, but it was changed several of years ago. I don't know in which version but I recall that I got the ClassCastException after installing a new Hibernate version and that I had to change my code.

that's why it's better if with use Number to handle the numeric return instead of using Long or Integer