Getting null pointer exception in first hibernate program. Please guide.

Dec 19, 2010 12:07:02 AM org.hibernate.annotations.common.Version <clinit>
INFO: Hibernate Commons Annotations 3.2.0.Final
Dec 19, 2010 12:07:02 AM org.hibernate.cfg.Environment <clinit>
INFO: Hibernate 3.6.0.Final
Dec 19, 2010 12:07:02 AM org.hibernate.cfg.Environment <clinit>
INFO: hibernate.properties not found
Dec 19, 2010 12:07:02 AM org.hibernate.cfg.Environment buildBytecodeProvider
INFO: Bytecode provider name : javassist
Dec 19, 2010 12:07:02 AM org.hibernate.cfg.Environment <clinit>
INFO: using JDK 1.4 java.sql.Timestamp handling
Dec 19, 2010 12:07:02 AM org.hibernate.cfg.Configuration configure
INFO: configuring from resource: /hibernate.cfg.xml
Dec 19, 2010 12:07:02 AM org.hibernate.cfg.Configuration getConfigurationInputStream
INFO: Configuration resource: /hibernate.cfg.xml
Dec 19, 2010 12:07:02 AM org.hibernate.util.DTDEntityResolver resolveEntity
WARNING: recognized obsolete hibernate namespace http://hibernate.sourceforge.net/. Use namespace http://www.hibernate.org/dtd/ instead. Refer to Hibernate 3.6 Migration Guide!
Dec 19, 2010 12:07:02 AM org.hibernate.cfg.Configuration addResource
INFO: Reading mappings from resource : contact.hbm.xml
Dec 19, 2010 12:07:02 AM org.hibernate.util.DTDEntityResolver resolveEntity
WARNING: recognized obsolete hibernate namespace http://hibernate.sourceforge.net/. Use namespace http://www.hibernate.org/dtd/ instead. Refer to Hibernate 3.6 Migration Guide!
Dec 19, 2010 12:07:02 AM org.hibernate.cfg.Configuration doConfigure
INFO: Configured SessionFactory: null
Exception in thread "main" java.lang.NullPointerException
at neha.firstHibernate.FirstExample.main(FirstExample.java:35)


hibernate.cfg.xml

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

<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">

com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">

jdbc:mysql://localhost/hibernatetutorial</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">858499</property>
<property name="hibernate.connection.pool_size">10</property>
<property name="show_sql">true</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.hbm2ddl.auto">update</property>
<!-- Mapping files -->
<mapping resource="contact.hbm.xml"/>
</session-factory>
</hibernate-configuration>

contach.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="roseindia.tutorial.hibernate.Contact" table="CONTACT">
<id name="id" type="long" column="ID" >
<generator class="assigned"/>
</id>

<property name="firstName">
<column name="FIRSTNAME" />
</property>
<property name="lastName">
<column name="LASTNAME"/>
</property>
<property name="email">
<column name="EMAIL"/>
</property>
</class>

<class name="roseindia.tutorial.hibernate.Book" table="book">
<id name="lngBookId" type="long" column="id" >
<generator class="increment"/>
</id>

<property name="strBookName">
<column name="bookname" />
</property>
</class>

<class name="roseindia.tutorial.hibernate.Insurance" table="insurance">
<id name="lngInsuranceId" type="long" column="ID" >
<generator class="increment"/>
</id>

<property name="insuranceName">
<column name="insurance_name" />
</property>
<property name="investementAmount">
<column name="invested_amount" />
</property>
<property name="investementDate">
<column name="investement_date" />
</property>
</class>



</hibernate-mapping>



Contact
package neha.firstHibernate;

public class Contact {
private String firstName;
private String lastName;
private String email;
private long id;

/**
* @return Email
*/
public String getEmail() {
return email;
}

/**
* @return First Name
*/
public String getFirstName() {
return firstName;
}

/**
* @return Last name
*/
public String getLastName() {
return lastName;
}

/**
* @param string Sets the Email
*/
public void setEmail(String string) {
email = string;
}

/**
* @param string Sets the First Name
*/
public void setFirstName(String string) {
firstName = string;
}

/**
* @param string sets the Last Name
*/
public void setLastName(String string) {
lastName = string;
}

/**
* @return ID Returns ID
*/
public long getId() {
return id;
}

/**
* @param l Sets the ID
*/
public void setId(long l) {
id = l;
}

}


Test

package neha.firstHibernate;

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


/**
* @author Deepak Kumar
*
* http://www.roseindia.net
* Hibernate example to inset data into Contact table
*/
public class FirstExample {
public static void main(String[] args) {
Session session = null;

try{
// This step will read hibernate.cfg.xml and prepare hibernate for use
SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
session =sessionFactory.openSession();
//Create new instance of Contact and set values in it by reading them from form object
System.out.println("Inserting Record");
Contact contact = new Contact();
contact.setId(3);
contact.setFirstName("Neha");
contact.setLastName("Khandelwal");
contact.setEmail("n.nehak@gmail.com");
session.save(contact);
System.out.println("Done");
}catch(Exception e){
System.out.println(e.getMessage());
}finally{
// Actual contact insertion will happen at this step
session.flush();
session.close();

}

}
}

You're indiscriminately flushing/closing the session in your finally block, but if either of these two lines throw an exception:

then session will be null, and this line:

will throw a NPE (which it's doing). This is hiding the original exception thrown. Quick fix:

Then you'll be able to see the real exception. Also, you're missing transaction control (session.beginTransaction(); tx.commit()/tx.rollback()).