java.lang.NullPointerException: EJB 2.0

[Hari Krishna Chaitanya Polukonda]

Hi All:

I am just trying out examples of entity beans. I am using JBOSS 4.0.0, EJB 2.0, MyEclipse 8.6. Reason for using JBOSS 4.0.0 and EJB 2.0 is just for learning sake. I am reading head first book. In the process help me if I made any mistakes. I wrote a build file using ant to deploy this in deploy directory of JBOSS. I also have login-config.xml, standardjaws.xml and jbosscmp-jdbc.xml file in my Meta-Inf directory. I am getting this error:

java.lang.NullPointerException
at org.jboss.ejb.plugins.local.LocalHomeProxy.invoke(LocalHomeProxy.java:118)
at $Proxy0.findByPrimaryKey(Unknown Source)
at AccesesPackage.DirectorMovie.go(DirectorMovie.java:24)
at AccesesPackage.DirectorMovie.main(DirectorMovie.java:13)

My ejb.jar file:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Enterprise JavaBeans 2.0//EN" "http://java.sun.com/dtd/ejb-jar_2_0.dtd"> 
<ejb-jar>
<display-name>EJB1</display-name>
<enterprise-beans>

<session>
<display-name>AdviceBean</display-name>
<ejb-name>AdviceBean</ejb-name>
<home>headfirst.AdviceHome</home>
<remote>headfirst.Advice</remote>
<ejb-class>headfirst.AdviceBean</ejb-class>
<session-type>Stateless</session-type>
<transaction-type>Bean</transaction-type>
</session>

<session>
<display-name>AdviceStatefullBean</display-name>
<ejb-name>AdviceStatefullBean</ejb-name>
<home>headfirstStatefull.AdviceHomeStatefull</home>
<remote>headfirstStatefull.AdviceStatefull</remote>
<ejb-class>headfirstStatefull.AdviceStatefullBean</ejb-class>
<session-type>Stateful</session-type>
<transaction-type>Bean</transaction-type>
</session>

<entity>
<display-name>MovieBean</display-name>
<ejb-name>MovieBean</ejb-name>
<local-home>movie.MovieHome</local-home>
<local>movie.Movie</local>
<ejb-class>movie.MovieBean</ejb-class>
<persistence-type>Container</persistence-type>
<prim-key-class>java.lang.Integer</prim-key-class>
<reentrant>False</reentrant>
<cmp-version>2.x</cmp-version>
<abstract-schema-name>movie</abstract-schema-name>
<cmp-field><field-name>movieId</field-name></cmp-field>
<cmp-field><field-name>title</field-name></cmp-field>
<cmp-field><field-name>year</field-name></cmp-field>
<cmp-field><field-name>genre</field-name></cmp-field>
<cmp-field><field-name>directorId</field-name></cmp-field>
<primkey-field>movieId</primkey-field>
<security-identity>
<use-caller-identity></use-caller-identity>
</security-identity>

<query>
<query-method>
<method-name>findByPrimaryKey</method-name>
<method-params>
<method-param>java.lang.Integer</method-param>
</method-params>
</query-method>
<ejb-ql>SELECT OBJECT (m) FROM movie m WHERE m.movieId = ?1</ejb-ql>
</query>

<query>
<query-method>
<method-name>findByGenre</method-name>
<method-params>
<method-param>java.lang.String</method-param>
</method-params>
</query-method>
<ejb-ql>SELECT OBJECT (m) FROM movie m WHERE m.genre = ?1</ejb-ql>
</query>

<query>
<query-method>
<method-name>ejbSelectGetAllMovies</method-name>
<method-params>
</method-params>
</query-method>
<ejb-ql>SELECT OBJECT (m) FROM movie m</ejb-ql>
</query>

</entity>

<entity>
<display-name>DirectorBean</display-name>
<ejb-name>DirectorBean</ejb-name>
<local-home>director.DirectorHome</local-home>
<local>director.Director</local>
<ejb-class>director.DirectorBean</ejb-class>
<persistence-type>Container</persistence-type>
<prim-key-class>java.lang.Integer</prim-key-class>
<reentrant>False</reentrant>
<cmp-version>2.x</cmp-version>
<abstract-schema-name>director</abstract-schema-name>
<cmp-field><field-name>directorId</field-name></cmp-field>
<cmp-field><field-name>oscarWinner</field-name></cmp-field>
<cmp-field><field-name>degrees</field-name></cmp-field>
<cmp-field><field-name>name</field-name></cmp-field>
<cmp-field><field-name>moviesByDirector</field-name></cmp-field>
<primkey-field>directorId</primkey-field>
<security-identity>
<use-caller-identity></use-caller-identity>
</security-identity>

<query>
<query-method>
<method-name>findByPrimaryKey</method-name>
<method-params>
<method-param>java.lang.Integer</method-param>
</method-params>
</query-method>
<ejb-ql>SELECT OBJECT (d) FROM director d WHERE d.directorId = ?1</ejb-ql>
</query>

<query>
<query-method>
<method-name>ejbSelectGetAllMovies</method-name>
<method-params>
<method-param>java.lang.Integer</method-param>
</method-params>
</query-method>
<ejb-ql>SELECT OBJECT (m) FROM movie m WHERE m.directorId = ?1</ejb-ql>
</query>
</entity>
</enterprise-beans>
<relationships>
<ejb-relation>
<ejb-relationship-role>
<ejb-relationship-role-name>DirectorBean</ejb-relationship-role-name>
<multiplicity>One</multiplicity>
<relationship-role-source><ejb-name>DirectorBean</ejb-name></relationship-role-source>
<cmr-field>
<cmr-field-name>moviesByDirector</cmr-field-name>
<cmr-field-type>java.util.Collection</cmr-field-type>
</cmr-field>
</ejb-relationship-role>

<ejb-relationship-role>
<ejb-relationship-role-name>MovieBean</ejb-relationship-role-name>
<multiplicity>Many</multiplicity>
<cascade-delete />
<relationship-role-source><ejb-name>MovieBean</ejb-name></relationship-role-source>
<cmr-field>
<cmr-field-name>Director</cmr-field-name>
<cmr-field-type>java.util.Collection</cmr-field-type>
</cmr-field>
</ejb-relationship-role>
</ejb-relation>
</relationships>
</ejb-jar>

My Jboss.xml is:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE jboss PUBLIC "-//JBoss//DTD JBOSS 3.2//EN" "http://www.jboss.org/j2ee/dtd/jboss_3_2.dtd">
<jboss>
<enterprise-beans>
<session>
<ejb-name>AdviceBean</ejb-name>
<jndi-name>Advisor</jndi-name>
</session>
<session>
<ejb-name>AdviceStatefullBean</ejb-name>
<jndi-name>AdvisorStatefull</jndi-name>
</session>
<entity>
<ejb-name>MovieBean</ejb-name>
<local-jndi-name>movies</local-jndi-name>
</entity>
<entity>
<ejb-name>DirectorBean</ejb-name>
<local-jndi-name>directors</local-jndi-name>
</entity>
</enterprise-beans>
</jboss>

In my director package I have these files:

director home:

package director;
import javax.ejb.*;
import java.util.*;
public interface DirectorHome extends EJBLocalHome {    
    public Director create(Integer directorId, boolean isOscar, Integer degrees, String name) throws CreateException ;    
    public Collection listOfActionMoviesByDirector(Integer directorId, String genre) throws FinderException;    
    public Collection listOfMoviesByDirector(Integer directorId) throws FinderException;    
    public Director findByPrimaryKey(Integer directorId) throws FinderException;    
    public String established();
}

director component interface:

package director;
import javax.ejb.*;
import java.util.*;
public interface Director extends EJBLocalObject {
	public void changeOscarStatus(boolean b);
}

director bean:

package director;
import java.rmi.RemoteException;
import javax.ejb.*;
import java.util.*;
import javax.sql.ConnectionPoolDataSource;
import javax.sql.PooledConnection;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import AccesesPackage.ConnectionPool;

public abstract class DirectorBean implements EntityBean {
	private EntityContext context;
	public void ejbActivate() {
		System.out.println("Inside ejb activate method");
	}
	public void ejbLoad() {
		System.out.println("Inside ejb activate method");
	}
	public void ejbPassivate()  {
		System.out.println("Inside ejb passivate method");
	}
	public void ejbRemove()  {
		System.out.println("Inside ejb remove method");
	}
	public void ejbStore() {
		System.out.println("Inside ejb store method");
	}
	public void setEntityContext(EntityContext arg0)  {
		this.context = arg0;
		System.out.println("Inside ejb set entity context method");
	}
	public void unsetEntityContext() {
		System.out.println("Inside ejb unset entity context method");
	}
	public abstract void setDirectorId(Integer id);
	public abstract Integer getDirectorId();
	public abstract void setOscarWinner(boolean b);
	public abstract boolean getOscarWinner();
	public abstract void setDegrees(Integer m);
	public abstract Integer getDegrees();
	public abstract void setName(String name);
	public abstract String getName();
	public abstract void setMoviesByDirector(Collection movies);
	public abstract Collection getMoviesByDirector();
	public abstract Collection ejbSelectGetAllMovies(Integer directorId) throws FinderException;
	public Collection ejbHomeListOfMoviesByDirector(Integer directorId){
		Collection col = null;
		try{
			col = this.ejbSelectGetAllMovies(directorId);
		}catch(Exception ex){
			ex.printStackTrace();
		}
		return col;
	}
	public Collection ejbHomeListOfActionMoviesByDirector(Integer directorId, String genre){
		return getMoviesByDirector();
	}
	public java.lang.Integer ejbCreate(Integer directorId, boolean isOscar, Integer degrees, String name) throws CreateException {
		this.setDirectorId(directorId);
		this.setOscarWinner(isOscar);
		this.setDegrees(degrees);
		this.setName(name);
		return directorId;
	}
	
	public void ejbPostCreate(Integer directorId, boolean isOscar, Integer degrees, String name) throws CreateException {
		this.setMoviesByDirector(this.ejbHomeListOfMoviesByDirector(directorId));
    }
	public void changeOscarStatus(boolean b){
		Connection con= null;
		try{
		Class.forName("com.mysql.jdbc.Driver").newInstance();
       	Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/ejbpr","root","chaitanya");
 	    String sql1 = "UPDATE director SET OscarWinner = ? where DirectorId = ?";
 	    PreparedStatement pstmt = conn.prepareStatement(sql1);
 	    pstmt.setBoolean(1, b);
 	    pstmt.setString(2, this.getDirectorId().toString());
		boolean update  = pstmt.execute();
		System.out.println(update);
		}catch(Exception ex){
			ex.printStackTrace();
		}
	}
	
	public String ejbHomeEstablished(){
		return "Connection established with stub";
	}
}

My movie package has following files:

movie home:

package movie;
import javax.ejb.*;
import java.util.*;
import java.rmi.*;
public interface MovieHome extends EJBLocalHome {
	public Movie create(Integer movieId, String title, Integer year, String genre, Integer directorId) throws CreateException;	
	public Movie findByPrimaryKey(Integer Key) throws FinderException;	
	public Collection findByGenre(String genre) throws FinderException;	
	public String listAllMovies() throws FinderException;
}

movie component interface:

package movie;
import javax.ejb.*;
public interface Movie extends EJBLocalObject {
	public String getMovieTitle();
}

movie bean:

package movie;
import java.rmi.RemoteException;
import javax.ejb.*;
import director.*;
import java.util.*;
import javax.naming.*;
public abstract class  MovieBean implements EntityBean {
	private EntityContext context = null;
	public void ejbActivate() {
		System.out.println("Inside ejb activate method");
	}
	public void ejbLoad()  {
		System.out.println("Inside ejb activate method");
	}
	public void ejbPassivate()  {
		System.out.println("Inside ejb passivate method");
	}
	public void ejbRemove()  {
		System.out.println("Inside ejb remove method");
	}
	public void ejbStore() {
		System.out.println("Inside ejb store method");
	}
	public void setEntityContext(EntityContext arg0)  {
		this.context = arg0;
		System.out.println("Inside ejb set entity context method");
	}
	public void unsetEntityContext()  {
		System.out.println("Inside ejb unset entity context method");
	}
	public String getMovieTitle(){
		return this.getTitle();
	}
	public abstract Integer getMovieId();
	public abstract void setMovieId(Integer movieId);
	public abstract String getTitle();
	public abstract void setTitle(String title);
	public abstract Integer getYear();
	public abstract void setYear(Integer year);
	public abstract String getGenre();
	public abstract void setGenre(String genre);
	public abstract void setDirectorId(Integer directorId);
	public abstract Integer getDirectorId();
	public abstract Director getDirector();
	public abstract void setDirector(Director director);
	public abstract Collection ejbSelectGetAllMovies() throws FinderException;
	public String ejbHomeListAllMovies(){
		String list = null;
		try{
			Collection movies = this.ejbSelectGetAllMovies();
			Iterator ita = movies.iterator();
			while(ita.hasNext()){
				Movie movie = (Movie) ita.next();
				list += " " + movie.getMovieTitle();
			}
		}catch(Exception exe){
			exe.printStackTrace();
		}
		return list;	
	}
	public java.lang.Integer ejbCreate(Integer movieId, String title, Integer year, String genre, Integer directorId) throws CreateException {
	   	this.setMovieId(movieId);
	   	this.setTitle(title);
	   	this.setYear(year);
	   	this.setGenre(genre);
	   	this.setDirectorId(directorId);
	    return movieId;
	}
	public void ejbPostCreate(Integer movieId, String title, Integer year, String genre, Integer directorId) throws CreateException{
		try{
			InitialContext ctx  = new InitialContext();
			DirectorHome dirhome = (DirectorHome) ctx.lookup("DirectorHome");
			Director dir = dirhome.findByPrimaryKey(directorId);
			this.setDirector(dir);
		}catch(Exception ex){
			ex.printStackTrace();
		}
	}

}

Finally I have a client class like this:

package AccesesPackage;
import javax.naming.*;
import java.rmi.*;
import javax.rmi.*;
import movie.*;
import director.*;
import javax.ejb.*;
import java.util.Properties;
public class DirectorMovie {
	public static void main(String[] args){
		new DirectorMovie().go();
	}
	public void go(){
		try{
			Properties properties = new Properties();
			properties.put("java.naming.factory.initial","org.jnp.interfaces.NamingContextFactory");
			properties.put("java.naming.factory.url.pkgs","org.jboss.naming:org.jnp.interfaces");
			properties.put("java.naming.provider.url","localhost:1099");
			Context ic = new InitialContext(properties);
			DirectorHome dir = (DirectorHome)ic.lookup("directors");
		    Director direct  = dir.findByPrimaryKey(new Integer("1"));
		    }catch(Exception ex){
			ex.printStackTrace();
		}
	}
}

Any help is greatly appreciated. I get some confidence going by solving this example.

Thank you in advance.

[Devaka Cooray]

Hari, it's hard to read this entire program. You will get more replies if you UseCodeTags and IsolateTheProblem. You can edit your topic by clicking the button.

[Hari Krishna Chaitanya Polukonda]

Hi Devak

I am new to javaranch. But any how I made the code more readable.

Thank you