Good day to all;

I'm developing a program using JSF2 and JPA2 (OpenJPA). Im also using IBM Rapid App Dev't v8 with WebSphere App Server v8 test server.
I have two simple entities, Employee and Department. Each Department has many Employees and each Employee belongs to a Department (using deptno and workdept). My problem occurs when i tried to add a new employee and selecting a department from a combo box (using selectOneMenu - populated from Department table):

when i run the program, the following error messages appeared:

An Error Occurred: java.lang.NullPointerException

Caused by: java.lang.NullPointerException - java.lang.NullPointerException

I also tried to make another program using Deptno and Workdept as String instead of integer, still doesn't work.

Pls help. Im also a newbie. Tnx and God bless.

Below are my codes, configurations and setup. Just tell me if there are some codes that I forgot to include.

Im also using Derby v10.5 as my database:

CREATE SCHEMA RTS;

CREATE TABLE RTS.DEPARTMENT
  (DEPTNO         INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),
   DEPTNAME       VARCHAR(30));

ALTER TABLE RTS.DEPARTMENT
  ADD CONSTRAINT PK_DEPARTMNET PRIMARY KEY (DEPTNO);

CREATE TABLE RTS.EMPLOYEE
  (EMPNO          INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),
   NAME           VARCHAR(50),
   WORKDEPT       INTEGER);

ALTER TABLE RTS.EMPLOYEE
  ADD CONSTRAINT PK_EMPLOYEE PRIMARY KEY (EMPNO);

Employee and Department Entities

package rts.entities;

import java.io.Serializable;
import javax.persistence.*;


@Entity
public class Employee implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int empno;

    private String name;

    //bi-directional many-to-one association to Department
    @ManyToOne
    @JoinColumn(name="WORKDEPT")
    private Department department;

    .......
    getter and setter methods



package rts.entities;

import java.io.Serializable;
import javax.persistence.*;
import java.util.List;


@Entity
public class Department implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int deptno;

    private String deptname;

    //bi-directional many-to-one association to Employee
    @OneToMany(mappedBy="department")
    private List<Employee> employees;

    .......
    getter and setter methods

JSF 2 snipet using combo box (populated from Department table)

<tr>
        <td align="left">Department</td>
        <td style="width: 5px">&#160;</td>
        <td><h:selectOneMenu styleClass="selectOneMenu"
        id="department1" value="#{pc_EmployeeAdd.employee.department}">
        <f:selectItems value="#{DepartmentManager.departmentSelectList}"
        id="selectItems1"></f:selectItems>
     </h:selectOneMenu></td>
</tr>



package rts.entities.controller;

import com.ibm.jpa.web.JPAManager;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import com.ibm.jpa.web.NamedQueryTarget;
import com.ibm.jpa.web.Action;
import javax.persistence.PersistenceUnit;
import javax.annotation.Resource;
import javax.transaction.UserTransaction;
import rts.entities.Department;
import java.util.List;
import javax.persistence.Query;
import java.util.ArrayList;
import java.text.MessageFormat;
import javax.faces.model.SelectItem;

@SuppressWarnings("unchecked")
@JPAManager(targetEntity = rts.entities.Department.class)
public class DepartmentManager {

.......

    public List<SelectItem> getDepartmentSelectList() {
        List<Department> departmentList = getDepartment();
        List<SelectItem> selectList = new ArrayList<SelectItem>();
        MessageFormat mf = new MessageFormat("{0}");
        for (Department department : departmentList) {
            selectList.add(new SelectItem(department, mf.format(
                    new Object[] { department.getDeptname() }, 
                    new StringBuffer(), null).toString()));
        }
        return selectList;
    }

Converter:

package rts.entities.converter;

import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;

import rts.entities.Department;
import rts.entities.controller.DepartmentManager;
import com.ibm.jpa.web.TypeCoercionUtility;

public class DepartmentConverter implements Converter {

    public Object getAsObject(FacesContext facesContext, UIComponent arg1,
            String entityId) {
        DepartmentManager departmentManager = (DepartmentManager) facesContext
                .getApplication().createValueBinding("#{DepartmentManager}")
                .getValue(facesContext);
        int deptno = (Integer) TypeCoercionUtility.coerceType("int", entityId);
        Department result = departmentManager.findDepartmentByDeptno(deptno);
        return result;
    }
    public String getAsString(FacesContext arg0, UIComponent arg1, Object object) {
        if (object instanceof Department) {
            return "" + ((Department) object).getDeptno();
        } else {
            throw new IllegalArgumentException("Invalid object type:"
                    + object.getClass().getName());
        }
    }
}

Method for Add button:

public String createEmployeeAction() { EmployeeManager employeeManager = (EmployeeManager) getManagedBean("EmployeeManager"); try { employeeManager.createEmployee(employee); } catch (Exception e) { logException(e); } return ""; }

faces-conf.xml

<converter>
    <converter-for-class>rts.entities.Department</converter-for-class>
    <converter-class>rts.entities.converter.DepartmentConverter</converter-class>
</converter>

Stack trace

javax.faces.FacesException: java.lang.NullPointerException
    at org.apache.myfaces.shared_impl.context.ExceptionHandlerImpl.wrap(ExceptionHandlerImpl.java:241)
    at org.apache.myfaces.shared_impl.context.ExceptionHandlerImpl.handle(ExceptionHandlerImpl.java:156)
    at org.apache.myfaces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:258)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:191)
    at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1147)
    at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:722)
    at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:449)
    at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:178)
    at com.ibm.ws.webcontainer.filter.WebAppFilterManager.invokeFilters(WebAppFilterManager.java:1020)
    at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:87)
    at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:886)
    at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1655)
    at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:195)
    at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:452)
    at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:511)
    at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:305)
    at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:276)
    at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:214)
    at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:113)
    at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
    at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
    at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
    at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:138)
    at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:204)
    at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:775)
    at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:905)
    at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1650)
Caused by: java.lang.NullPointerException
    at rts.entities.converter.DepartmentConverter.getAsString(DepartmentConverter.java:29)
    at org.apache.myfaces.shared_impl.renderkit.RendererUtils.getConvertedStringValue(RendererUtils.java:656)
    at org.apache.myfaces.shared_impl.renderkit.html.HtmlRendererUtils.getSubmittedOrSelectedValuesAsSet(HtmlRendererUtils.java:444)
    at org.apache.myfaces.shared_impl.renderkit.html.HtmlRendererUtils.internalRenderSelect(HtmlRendererUtils.java:421)
    at org.apache.myfaces.shared_impl.renderkit.html.HtmlRendererUtils.renderMenu(HtmlRendererUtils.java:359)
    at org.apache.myfaces.shared_impl.renderkit.html.HtmlMenuRendererBase.encodeEnd(HtmlMenuRendererBase.java:76)
    at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:519)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:626)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:622)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:622)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:622)
    at org.apache.myfaces.view.facelets.FaceletViewDeclarationLanguage.renderView(FaceletViewDeclarationLanguage.java:1320)
    at org.apache.myfaces.application.ViewHandlerImpl.renderView(ViewHandlerImpl.java:263)
    at org.apache.myfaces.lifecycle.RenderResponseExecutor.execute(RenderResponseExecutor.java:85)
    at org.apache.myfaces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:239)
    ... 24 more