JPA - Hibernate - query.getResultList() returns 3 null values.

[Sharad Kharya]

I am new to JPA and developing my 1st JPA application with using MySQL DB and hibernate as persistence provider.

I created a Table with 3 rows.
When i am using JDBC approach, i am getting all the results correctly

But, when i use JPA mechanism, the query.getResultList() returns 3 null values.

I didn't understand where i did a mistake
Please help in resolving the issue -

Code/Schema details -
Schema details -

CREATE SCHEMA `JPADB` ;
CREATE  TABLE `jpadb`.`JPA1` (   `idJPA1` INT NOT NULL ,   `fname` VARCHAR(45) NULL DEFAULT 'Sharad' ,   `lname` VARCHAR(45) NULL DEFAULT 'Kharya' ,   PRIMARY KEY (`idJPA1`) ); 
INSERT INTO `jpadb`.`JPA1` (`idJPA1`, `fname`, `lname`) VALUES (1, 'S', 'K'); 
INSERT INTO `jpadb`.`JPA1` (`idJPA1`, `fname`, `lname`) VALUES (2, 'Sharad', 'Kharya'); 
INSERT INTO `jpadb`.`JPA1` (`idJPA1`, `fname`, `lname`) VALUES (3, 'Sh', 'Kh'); 

Code using JDBC approach - Test_Connection.java

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;


public class Test_Connection {

	public static void main (String[] args)
    {
        Connection conn = null;
        try
        {
            String userName = "root";
            String password = "root";
            String url = "jdbc:mysql://localhost/JPADB"; //Server/DBname
            Class.forName ("com.mysql.jdbc.Driver").newInstance ();
            conn = DriverManager.getConnection (url, userName, password);
            System.out.println ("Database connection established");
            Statement st = conn.createStatement();
            ResultSet rs = st.executeQuery("select * from JPA1");
            while(rs.next()){
            	String idNew_Table = rs.getString(1);
            	String fName = rs.getString(2); //2=fname i.e 2nd column value
            	String lName = rs.getString("lname");
            	
            	System.out.println("id="+idNew_Table);
				System.out.println("fname="+fName);
				System.out.println("lname="+lName);
            	
            }
        }
        catch (Exception e)
        {
        	e.printStackTrace();
            System.err.println ("Cannot connect to database server");
        }
        finally
        {
            if (conn != null)
            {
                try
                {
                    conn.close ();
                    System.out.println ("Database connection terminated");
                }
                catch (Exception e) { /* ignore close errors */ }
            }
        }
    }


}

Output -

Database connection established
id=1
fname=S
lname=K
id=2
fname=Sharad
lname=Kharya
id=3
fname=Sh
lname=Kh
Database connection terminated

Now JPA appraoch codes -
persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence>
 <persistence-unit name="jpa1">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <class>com.sk.jpa.JPA_Class</class>
    <properties>
        <property name="hibernate.connection.url" value="jdbc:mysql://localhost/JPADB"/>
        <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
        <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
        <property name="hibernate.connection.password" value="root"/>
        <property name="hibernate.connection.username" value="root"/>
        <property name="hibernate.hbm2ddl.auto" value="update"/>
        <property name="hibernate.show_sql" value="true"/>
        <!--
        <property name="hibernate.format_sql" value="true"/>
        -->
    </properties>
  </persistence-unit> 
</persistence>

Entity class - JPA_Class.java

package com.sk.jpa;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="JPA1")
public class JPA_Class {

	@Id
	@GeneratedValue
	private int id;
	
	@Column(name="fname")
	private String fname;
	
	private String lname;

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getFname() {
		return fname;
	}

	public void setFname(String fname) {
		this.fname = fname;
	}

	public String getLname() {
		return lname;
	}

	public void setLname(String lname) {
		this.lname = lname;
	}

}

Reading data code - read.java

package com.sk.jpa;

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

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;

public class read {

	public static void main(String[] args) {
		
		EntityManagerFactory emf = Persistence.createEntityManagerFactory("jpa1");
		EntityManager em = emf.createEntityManager();
		
		try
		{
			em.getTransaction().begin();
			Query q = em.createQuery("SELECT j FROM JPA_Class j");
			List l = q.getResultList();
			Iterator i = l.iterator();
			System.out.println("================count of result="+l.size());
                        System.out.println("list returend values ="+l);
			while(i.hasNext())
			{
				JPA_Class jpa1Obj = (JPA_Class)i.next();
				System.out.println("id="+jpa1Obj.getId());
				System.out.println("fname="+jpa1Obj.getFname());
				System.out.println("lname="+jpa1Obj.getLname());
			}
			
			
			em.getTransaction().commit();
		}catch (Exception e) {
			em.getTransaction().rollback();
			e.printStackTrace();
		}
	}
}

Out of JPA logic when exected-

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.annotations.Version).
log4j:WARN Please initialize the log4j system properly.
Hibernate: select jpa_class0_.id as id0_, jpa_class0_.fname as fname0_, jpa_class0_.lname as lname0_ from JPA1 jpa_class0_
================count of result=3
list returend values =[null, null, null]
java.lang.NullPointerException
	at com.sk.jpa.read.main(read.java:30)

[Sharad Kharya]

This got resolved -

i missed the mapping of id/prymary key with column name in Entity class.
line added -

public class JPA_Class {

	@Id
	@GeneratedValue
	@Column(name="idJPA1")
	private int id;
	.....