All,

I'm trying to build a simple list based on a lookup table using:
Hibernate 3.2
MySQL 5.0.37
Java 1.6

I tried to use the following code to list all of the members:
List custGroups = session.createQuery("SELECT id,name FROM test.CustomerGroup").list();
session.getTransaction().commit();

System.out.println("list : " + custGroups);

Iterator it = custGroups.iterator();
while (it.hasNext()) {
custGroup = (CustomerGroup) it.next();
//Object obj = it.next();
System.out.println("obj : " + custGroup);
cg = new SelectItem(custGroup,custGroup.getName());
cgs.add(cg);
}

I get a class cast exception. The objects in the list are java.lang.Object, not test.CustomerGroup. The query works:

Hibernate: select customergr0_.id as col_0_0_, customergr0_.custGroup as col_1_0_ from servercustGroup customergr0_
list : [[Ljava.lang.Object;@e06ce, [Ljava.lang.Object;@e0f0ad, [Ljava.lang.Object;@1d8f162, [Ljava.lang.Object;@1cf662f]

There are four results, four entries in the table, but why aren't they being mapped to test.CustGroup?

I have the following config:

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

<session-factory>

<!-- Database connection settings -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost/trend102</property>
<property name="connection.username">root</property>
<property name="connection.password"></property>

<!-- JDBC connection pool (use the built-in) -->
<property name="connection.pool_size">1</property>

<!-- SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>

<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>

<!-- Disable the second-level cache -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

<!-- Echo all executed SQL to stdout -->
<property name="show_sql">true</property>

<!-- Drop and re-create the database schema on startup -->
<!-- <property name="hbm2ddl.auto">create</property> -->

<mapping file="/home/mlb/apps/tomcat/webapps/jsf-test/WEB-INF/hibernate.xml"/>

</session-factory>

</hibernate-configuration>

and the following mapping:

<hibernate-mapping>
<class name="test.CustomerGroup" table="servercustGroup">
<id name="id" column="id" type="integer">
<generator class="native" />
</id>
<property name="name" type="string" column="custGroup" />
</class>
</hibernate-mapping>

Any help would be appreciated

Hi,
Hibernate will return a list of Object[] ( array) ; example

Object[] obj = {1,"name"}


so you returned object is not CustomerGroup but rather Object[]


try with this


Object[] obj = (Object[] ) it.next();
System.out.println("id-->" + obj[0]);
System.out.println("name-->" + obj[1]);


if your query is


SELECT name FROM test.CustomerGroup
then your returned list is a String
which will be

String name = (String ) it.next();

and if your query is like

SELECT id FROM test.CustomerGroup
then the list will be Long datatype
which become

Long id= (Long) it.next();


I hope this could help

Another quick troubleshooting tip might just be to find out what the object type is in that List. So, do something like this inside your looP:

System.out.println(obj[i].getClass());

Then you'll know for sure what the object type is. Then you can begin to handle your data with a bit more knowledge of what Hibernate3 is returning to you.