Hi,
I am trying to run a sample stand alone hibernate program. I am using hibernate3 with MySql database. I am getting the following exception when run.

[i]java.lang.NullPointerException
at org.hibernate.jdbc.AbstractBatcher.closeConnection(AbstractBatcher.ja
va:505)
at org.hibernate.engine.TransactionHelper.doWorkInNewTransaction(Transac
tionHelper.java:142)
at org.hibernate.id.TableGenerator.generate(TableGenerator.java:94)
at org.hibernate.id.TableHiLoGenerator.generate(TableHiLoGenerator.java:
61)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId
(AbstractSaveEventListener.java:91)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGene
ratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:186)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrR
equestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTran
sient(DefaultSaveOrUpdateEventListener.java:175)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(
DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpda
te(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:524)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:514)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:510)
at Test.main(Test.java:17)[/i]

It says the problem is with line 17 in Test.java
Test.java is below

[code]public class Test
{

public static void main(String args[])
{
try
{
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
Session session = sessionFactory.openSession();
CD cd = new CD();
cd.setId(1);cd.setTitle("Ravi");cd.setArtist("Kumar");cd.setPurchasedate(new Date());cd.setCost(4.33);
session.save(cd); // [b]problem here[/b]
session.flush();
session.close();
} catch (Exception e)
{
e.printStackTrace();
}
}
}[/code]

The mapping file is

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

[code]<hibernate-mapping>
<class name="CD" table="cd">
<id name="id" type="int">
<column name="ID"/>
<generator class="hilo"/>
</id>
<property name="title"/>
<property name="artist"/>
<property name="purchasedate" type="date"/>
<property name="cost" type="double"/>
</class>
</hibernate-mapping>[/code]

Please guide how to get rid of this exception.

Thanks
Ravi Kumar

[/i]

Does



and a later commt help ?

You don't have any open JDBC connections!

For a simple testing standalone app like this, you need to have some code BEFORE the sessionFactory.openSession() which gets you a JDBC connection. Look up JDBC to see how to get a JDBC connection object for your database. Then you can do sessionFactory.openSession(connection). Then it will work. Remember to do connection.close() after you do session.close().

I have never seen any hibernate application needs jdbc connection.
And opening a transation and commiting is also optional. There must me some thing else as root of the problem. Please anybody try to help me. I am struggling since yesterday...


Thanks
Ravi Kumar

You are using the wrong dtd in your mapping:



If you are really using hibernate3 it should
be like:



And can you post your hibernate.cfg.xml ?

Look at the full source code. Where is the JDBC connection coming from in this case?

What does your hibernate.properties or hibernate.cfg.xml look like. I am using Hibernate 2 and includes properties like the following for MySQL

hibernate.connection.driver_class=com.mysql.jdbc.Driver
hibernate.connection.password=password
hibernate.connection.url=jdbc\:mysql\://127.0.0.1\:3306/test
hibernate.connection.username=root
hibernate.dialect=net.sf.hibernate.dialect.MySQLDialect
hibernate.show_sql=true