ClassCastException in iterating list returned by Query using Hibernate Query Language

Question

I'm beginner in hibernate.I'm trying a simplest example using HQL but it generates exception at line 25 ClassCastException when i try to iterate list.When i try to cast the object returned by next() methode of iterator it generates the same problem.I could not identify the problem.Kindly give me solution of the problem.

Employee.java

package one;

import javax.persistence.Entity;
import javax.persistence.Id;

@Entity
public class Employee {
@Id
private Long id;
private String name;
public Long getId() {
    return id;
}
public void setId(Long id) {
    this.id = id;
}
public String getName() {
    return name;
}
public void setName(String name) {
    this.name = name;
}
public Employee(Long id, String name) {
    super();
    this.id = id;
    this.name = name;
}
public Employee()
{

}

 } 


Main2.java

package one;

import java.util.Iterator;
import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;

public class Main2 {

public static void main(String[] args) {

    SessionFactory sf=new Configuration().configure().buildSessionFactory();
    Session s1=sf.openSession();
    Query q=s1.createQuery("from Employee ");
    Transaction tx=s1.beginTransaction();

    List l=q.list();
    Iterator itr=l.iterator();
    while(itr.hasNext())
    {
        Object obj[]=(Object[])itr.next();//Line 25 
        for(Object temp:obj)
        {
        System.out.println(temp);   
        }
    }

    tx.commit();
    s1.close();
    sf.close();

}

}

Andreas Aumayr · Accepted Answer · 2013-11-13 09:50:45Z

1

It should be

Employee emp =(Employee)itr.next();//Line 25

you select all employees ("from Employee") and iterate over the result list that contains all your Employee entities. There's no need to cast to object[].

The for loop within the iteration loop should be obsolete as well.

EDIT: The following code should do what you intended it to do.

List l=q.list(); // you retrieve a List of Employee entities (the result of your query)
Iterator itr=l.iterator();
while(itr.hasNext())
{
    Employee emp = (Employee)itr.next();
    System.out.println(emp);   
    }
}

An alternative to the iterator may be an indexed for loop like:

for(int i = 0; i<l.size(); i++){
  Employee emp = (Employee)l.get(i);
  System.out.println(emp);
}

edited Nov 13, 2013 at 9:50

answered Nov 13, 2013 at 9:01

Andreas Aumayr

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2 Comments

Tushar Paliwal Over a year ago

Thanks for the solution but if i try to get result using my code.Is it wrong?I also want to know mistake in my code.

Andreas Aumayr Over a year ago

I edited my answer. Does this answer your question? If not: please refine your question as it is hard to understand what you really want.

Chowdappa · Accepted Answer · 2013-11-13 09:05:55Z

0

next() in Iterator will return one of the objects from list. So, it should be like below:

Employee e =(Employee)itr.next();

if you use generic type, even you no need to cast again.

answered Nov 13, 2013 at 9:05

Chowdappa

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