[Help] Null Pointer Exception in session.flush() Hibernate

[Fandy Akhmad]

Dear All masters Java..

I learn Hibernate Framework, and try made simple application to insert data into Database.
I get error like this :

Exception in thread "main" java.lang.NullPointerException
at com.fandezign.training.hibernate.TestHibernate.main(TestHibernate.java:45)

And line 45 is pointing to session.flush(); statement.

Here is my code :

package com.fandezign.training.hibernate;

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

/**
 * Nov 26, 2011 , Indonesia
 * @author Fandi Akhmad
 * Package	: com.fandezign.training.hibernate
 * Filename	: TestHibernate.java
 */
public class TestHibernate {
	public static void main(String args[]) {
		Session session = null;
		
		try {
			// Memanggil hibernate.cfg.xml dan menyiapkan hibernate untuk segera digunakan.
			SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
			
			// Buka session
			session = sessionFactory.openSession();
			
			// Membuat instans dari Class User, dan mengeset nilainya dengan membaca dari form objek.
			System.out.println("Inserting Record...");
			
			User user = new User();
			user.setFirstName("Jackie");
			user.setLastName("Chan");
			
			// save
			session.save(user);
			System.out.println("Done!");
		}catch(Exception se) {
			System.out.println(se.getMessage());
		}finally {
			session.flush();
			session.close();
		}
	}
}

I hope all master's help and guidance.

Thank you.

[Vijitha Kumara]

Welcome to the CodeRanch!

Do you have any other code in the same file? Given is less than 45 lines of code... And do you get the record in the DB after running the code?

[Fandy Akhmad]

Hello, thanks for your respond

I try to add condition like this in finally block.

if(session != null) {
	session.flush();
	session.close();
}

And problem solved. But new problem shown and many error.
This is error code :

31 [main] INFO org.hibernate.cfg.Environment - Hibernate 3.3.0.GA
31 [main] INFO org.hibernate.cfg.Environment - hibernate.properties not found
47 [main] INFO org.hibernate.cfg.Environment - Bytecode provider name : javassist
47 [main] INFO org.hibernate.cfg.Environment - using JDK 1.4 java.sql.Timestamp handling
125 [main] INFO org.hibernate.cfg.Configuration - configuring from resource: /hibernate.cfg.xml
125 [main] INFO org.hibernate.cfg.Configuration - Configuration resource: /hibernate.cfg.xml
265 [main] INFO org.hibernate.cfg.Configuration - Reading mappings from resource : User.hbm.xml
453 [main] INFO org.hibernate.cfg.HbmBinder - Mapping class: com.fandezign.training.hibernate.User -> tbl_user
484 [main] INFO org.hibernate.cfg.Configuration - Configured SessionFactory: null
578 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - Using Hibernate built-in connection pool (not for production use!)
578 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - Hibernate connection pool size: 10
578 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - autocommit mode: false
593 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - using driver: com.mysql.jdbc.Driver at URL: jdbc:mysql://localhost/employee
593 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - connection properties: {user=root, password=****}
1078 [main] INFO org.hibernate.cfg.SettingsFactory - RDBMS: MySQL, version: 5.1.41
1078 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC driver: MySQL-AB JDBC Driver, version: mysql-connector-java-5.1.18 ( Revision: [e-mail]-20110930151701-jfj14ddfq48ifkfq )
1109 [main] INFO org.hibernate.dialect.Dialect - Using dialect: org.hibernate.dialect.MySQLDialect
1109 [main] INFO org.hibernate.transaction.TransactionFactoryFactory - Using default transaction strategy (direct JDBC transactions)
1109 [main] INFO org.hibernate.transaction.TransactionManagerLookupFactory - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended)
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Automatic flush during beforeCompletion(): disabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Automatic session close at end of transaction: disabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC batch size: 15
1109 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC batch updates for versioned data: disabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Scrollable result sets: enabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC3 getGeneratedKeys(): enabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Connection release mode: auto
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Maximum outer join fetch depth: 2
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Default batch fetch size: 1
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Generate SQL with comments: disabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Order SQL updates by primary key: disabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Order SQL inserts for batching: disabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory
1109 [main] INFO org.hibernate.hql.ast.ASTQueryTranslatorFactory - Using ASTQueryTranslatorFactory
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Query language substitutions: {}
1109 [main] INFO org.hibernate.cfg.SettingsFactory - JPA-QL strict compliance: disabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Second-level cache: enabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Query cache: disabled
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Cache region factory : org.hibernate.cache.impl.NoCachingRegionFactory
1109 [main] INFO org.hibernate.cfg.SettingsFactory - Optimize cache for minimal puts: disabled
null
1125 [main] INFO org.hibernate.cfg.SettingsFactory - Structured second-level cache entries: disabled
1125 [main] INFO org.hibernate.cfg.SettingsFactory - Echoing all SQL to stdout
1125 [main] INFO org.hibernate.cfg.SettingsFactory - Statistics: disabled
1125 [main] INFO org.hibernate.cfg.SettingsFactory - Deleted entity synthetic identifier rollback: disabled
1125 [main] INFO org.hibernate.cfg.SettingsFactory - Default entity-mode: pojo
1125 [main] INFO org.hibernate.cfg.SettingsFactory - Named query checking : enabled
1218 [main] INFO org.hibernate.impl.SessionFactoryImpl - building session factory
1500 [main] INFO org.hibernate.impl.SessionFactoryObjectFactory - Not binding factory to JNDI, no JNDI name configured

And you may want to see my Hibernate and POJO file.

Here is my User.java

/**
 * Nov 26, 2011 , Indonesia
 * @author Fandi Akhmad
 * Package	: com.fandezign.training.hibernate
 * Filename	: User.java
 */
package com.fandezign.training.hibernate;

/**
 * Nov 26, 2011 , Indonesia
 * @author Fandi Akhmad
 * Package	: com.fandezign.training.hibernate
 * Filename	: User.java
 */
public class User {
	private int id;
	private String firstName;
	private String lastName;
	
	
	
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	
	public String getFirstName() {
		return firstName;
	}
	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}
	
	public String getLastName() {
		return lastName;
	}
	public void setLastName(String lastName) {
		this.lastName = lastName;
	}
}

Here is my hibernate.cfg.xml

<?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>
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost/employee</property>
        <property name="connection.username">root</property>
        <property name="connection.password"></property>
        <property name="connection.pool_size">10</property>
        <property name="show_sql">true</property>
        <property name="hbmddl.auto">update</property>
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        
        <!-- Mapping Files -->
        <mapping resource="User.hbm.xml" />
    </session-factory>
</hibernate-configuration>

Here is my User.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">
<!-- Generated Nov 26, 2011 10:55:56 PM by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
    <class name="com.fandezign.training.hibernate.User" table="tbl_user">
        <id name="id" type="int">
            <column name="id" />
            <generator class="native" />
        </id>
        <property name="firstName">
            <column name="first_name" />
        </property>
        <property name="lastName">
            <column name="last_name" />
        </property>
    </class>
</hibernate-mapping>

Here is my TestHibernate.java file

/**
 * Nov 26, 2011 , Indonesia
 * @author Fandi Akhmad
 * Package	: com.fandezign.training.hibernate
 * Filename	: TestHibernate.java
 */
package com.fandezign.training.hibernate;


import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Nov 26, 2011 , Indonesia
 * @author Fandi Akhmad
 * Package	: com.fandezign.training.hibernate
 * Filename	: TestHibernate.java
 */
public class TestHibernate {
	public static void main(String args[]) {
		
		Logger logger = LoggerFactory.getLogger(TestHibernate.class);
		
		Session session = null;
		
		try {
			// Memanggil hibernate.cfg.xml dan menyiapkan hibernate untuk segera digunakan.
			SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
			
			Transaction trs = session.beginTransaction();
			
			// Buka session
			session = sessionFactory.openSession();
			
			// Membuat instans dari Class User, dan mengeset nilainya dengan membaca dari form objek.
			System.out.println("Inserting Record...");
			
			User user = new User();
			user.setFirstName("Jackie");
			user.setLastName("Chan");
			
			// save
			session.save(user);
			
			session.beginTransaction().commit();
			
			System.out.println("Done!");
		}catch(Exception se) {
			System.out.println(se.getMessage());
		}finally {
			if(session != null) {
				session.flush();
				session.close();
			}
		}
	}
}

Please help me,..
Thanks before...

[James Boswell]

Between the lines

Session session = null;

and

Transaction trs = session.beginTransaction();

I don't see where session is initialized.

[Vijitha Kumara]

There's no errors in the snippet of the log you posted. And you begin the transaction after the save() is executed? I suggest you read the getting started guide in the documentation here.

[Fandy Akhmad]

Thanks for your help

It Works..!

I try to remove line code

Transaction trs = session.beginTransaction();

and replace with

session.beginTransaction();