AbstractWizardFormController: java.lang.NullPointerException at processFinish(...)

Question

Hi, Could someone please help me understand that why am I getting this error at RegisterServiceProviderController.java when processFinish(...) method is called?

java.lang.NullPointerException
 at com.inception.web.RegisterServiceProviderController.processFinish(RegisterServiceProviderController.java:66)
 at org.springframework.web.servlet.mvc.AbstractWizardFormController.validatePagesAndFinish(AbstractWizardFormController.java:642)
 at org.springframework.web.servlet.mvc.AbstractWizardFormController.processFormSubmission(AbstractWizardFormController.java:492)
 at org.springframework.web.servlet.mvc.AbstractFormController.handleRequestInternal(AbstractFormController.java:265)
 at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:153)
 at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:48)
 at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:875)
 at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:809)
 at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:476)
 at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:441)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
 at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:849)
 at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
 at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:454)
 at java.lang.Thread.run(Thread.java:619)

Following are all the files needed to run this simple application: RegisterServiceProviderController.java

package com.inception.web;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.orm.hibernate3.HibernateTemplate;
import org.springframework.validation.BindException;
import org.springframework.validation.Errors;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractWizardFormController;

import com.inception.bean.ExtendedServiceProvider;
import com.inception.domain.BusinessLocation;
import com.inception.domain.ServiceProvider;
import com.inception.domain.State;
import com.inception.service.ServiceProviderService;

public class RegisterServiceProviderController extends AbstractWizardFormController{

 protected Object formBackingObject(HttpServletRequest request) throws Exception {
  ExtendedServiceProvider extendedServiceProvider = (ExtendedServiceProvider) super.formBackingObject(request);

  ServiceProvider serviceProvider = new ServiceProvider();

  Set<BusinessLocation> businessLocations = new HashSet<BusinessLocation>();
  BusinessLocation businessLocation = new BusinessLocation();
  businessLocation.setState(new State());
  businessLocations.add(businessLocation);
  serviceProvider.setBusinessLocations(businessLocations);

  extendedServiceProvider.setServiceProvider(serviceProvider);  

  return extendedServiceProvider;
 }
 protected Map referenceData(HttpServletRequest request, Object command, Errors errors, int page) throws Exception {
  ExtendedServiceProvider extendedServiceProvider = (ExtendedServiceProvider) command;
  Map refData = new HashMap();
  refData.put("currentLocationNumber", extendedServiceProvider.getServiceProvider().getBusinessLocations().size());
  refData.put("locationIndex", extendedServiceProvider.getServiceProvider().getBusinessLocations().size() - 1);
  refData.put("stateData", hibernateTemplate.find("from StateData"));
  return refData;
 }

 protected void postProcessPage(HttpServletRequest request, Object command, Errors errors, int page) throws Exception {
  ExtendedServiceProvider extendedServiceProvider = (ExtendedServiceProvider) command;
  if(page == 1 && request.getParameter("_target1") != null) {
   BusinessLocation businessLocation = new BusinessLocation();
   businessLocation.setState(new State());
   extendedServiceProvider.getServiceProvider().getBusinessLocations().add(businessLocation);   
  }
 }

 protected ModelAndView processFinish(HttpServletRequest request,
   HttpServletResponse response, Object command, BindException errors)
   throws Exception {

  ExtendedServiceProvider extendedServiceProvider = (ExtendedServiceProvider) command;

  //the last business location is always blank... remove it
  extendedServiceProvider.getServiceProvider().getBusinessLocations().remove(extendedServiceProvider.getServiceProvider().getBusinessLocations().size() - 1);
  serviceProviderService.addServiceProvider(extendedServiceProvider.getServiceProvider());

  return new ModelAndView(getSuccussView(), "serviceProvider", extendedServiceProvider.getServiceProvider());
 } 

 private String getSuccussView() {
  return getPages()[getPages().length - 1];
 }

 private ServiceProviderService serviceProviderService;
 public void setServiceProviderService(ServiceProviderService serviceProviderDAO) {
  this.serviceProviderService = serviceProviderService;
 }

 private HibernateTemplate hibernateTemplate;
 public void setHibernateTemplate(HibernateTemplate hibernateTemplate) {
  this.hibernateTemplate = hibernateTemplate;
 }

}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>springmvc</display-name>
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
    </servlet>
    <context-param>
  <param-name>contextConfigLocation</param-name>
  <param-value>/WEB-INF/dispatcher-servlet.xml</param-value>
 </context-param>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>*.htm</url-pattern>
    </servlet-mapping>

 <servlet>
  <servlet-name>dwr</servlet-name>
  <servlet-class>org.directwebremoting.spring.DwrSpringServlet</servlet-class>
  <init-param>
   <param-name>debug</param-name>
   <param-value>true</param-value>
  </init-param>
 </servlet> 
 <servlet-mapping>
  <servlet-name>dwr</servlet-name>
  <url-pattern>/dwr/*</url-pattern>
 </servlet-mapping>

 <listener>
  <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
 </listener>
</web-app>

dispatcher-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns:dwr="http://www.directwebremoting.org/schema/spring-dwr"
 xsi:schemaLocation="http://www.springframework.org/schema/beans 
      http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
      http://www.directwebremoting.org/schema/spring-dwr
      http://www.directwebremoting.org/schema/spring-dwr-2.0.xsd"&gt;

 <!-- DWR configuration -->
 <dwr:configuration >
  <dwr:convert type="bean" class="com.inception.domain.User" />
 </dwr:configuration>

 <!-- Resource bundle -->
    <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
        <property name="basename" value="messages"/>
    </bean>

    <!-- Data source -->
    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/springmvc"/>
        <property name="username" value="root"/>
        <property name="password" value="password"/>
    </bean>

    <!-- Session factory -->
 <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
  <property name="dataSource" ref="dataSource"/>

  <property name="annotatedClasses">
   <list>
    <value>com.inception.domain.ServiceProvider</value>
    <value>com.inception.domain.BusinessLocation</value>
    <value>com.inception.domain.State</value>
    <value>com.inception.domain.StateData</value> 
   </list>
  </property>

  <property name="hibernateProperties">
   <props>
    <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
    <prop key="hibernate.hbm2ddl.auto">create</prop>
    <prop key="hibernate.show_sql">true</prop>
   </props>
  </property>

 </bean>

 <!-- View resolver -->
 <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
  <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
  <property name="prefix" value="/WEB-INF/jsp/" />
  <property name="suffix" value=".jsp" />
 </bean>

 <!-- Mapping handler -->
 <bean id="publicUrlMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
  <property name="mappings">
   <value>
    /register.htm=registerServiceProviderController
    /home.htm=homePageController
   </value>  
  </property>
  <property name="interceptors">
   <bean class="com.inception.interceptor.LoggingInterceptor" />
  </property>
 </bean>

 <!-- Controllers-->

 <bean id="registerServiceProviderController" class="com.inception.web.RegisterServiceProviderController">
  <property name="commandClass" value="com.inception.bean.ExtendedServiceProvider" />
  <property name="commandName" value="extendedServiceProvider" />
  <property name="sessionForm" value="true" />
  <property name="serviceProviderService" ref="serviceProviderService" />
  <property name="hibernateTemplate" ref="hibernateTemplate" />
  <property name="pages">
   <list>
    <value>numberOfLocationForm</value>
    <value>locationDetailForm</value>
    <value>registrationConfirmationForm</value>
    <value>redirect:home.htm</value>
   </list>
  </property>
 </bean>

 <bean id="homePageController" class="com.inception.web.HomePageController" />

 <!-- Services -->
 <bean id="serviceProviderService" class="com.inception.service.ServiceProviderServiceImpl">
  <property name="serviceProviderDAO" ref="serviceProviderDAO" />
 </bean>

 <!-- DAOs -->
 <bean id="serviceProviderDAO" class="com.inception.dao.ServiceProviderDAOImpl">
  <property name="hibernateTemplate" ref="hibernateTemplate" />
 </bean>

 <!-- Templates -->
 <bean id="hibernateTemplate" class="org.springframework.orm.hibernate3.HibernateTemplate">
  <property name="sessionFactory" ref="sessionFactory" />
 </bean> 
</beans>

ExtendedServiceProvider.java

package com.inception.bean;

import java.io.Serializable;

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

import com.inception.domain.ServiceProvider;

public class ExtendedServiceProvider implements Serializable{

 private Long locationCount;
 private ServiceProvider serviceProvider; 

 public Long getLocationCount() {
  return locationCount;
 }
 public void setLocationCount(Long locationCount) {
  this.locationCount = locationCount;
 }
 public ServiceProvider getServiceProvider() {
  return serviceProvider;
 }
 public void setServiceProvider(ServiceProvider serviceProvider) {
  this.serviceProvider = serviceProvider;
 }
}

BusinessLocation.java

package com.inception.domain;

import java.io.Serializable;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;

@Entity
public class BusinessLocation implements Serializable{

 private Long id;
 private String address;
 private String city;
 private State state;
 private String pincode;
 private ServiceProvider serviceProvider;

 public BusinessLocation() {  
 }

 @Id
 @GeneratedValue
 public Long getId() {
  return id;
 }
 public void setId(Long id) {
  this.id = id;
 }
 public String getAddress() {
  return address;
 }
 public void setAddress(String address) {
  this.address = address;
 }
 public String getCity() {
  return city;
 }
 public void setCity(String city) {
  this.city = city;
 }

 @ManyToOne
 @JoinColumn(name="state_id")
 public State getState() {
  return state;
 }
 public void setState(State state) {
  this.state = state;
 } 
 public void setPincode(String pincode) {
  this.pincode = pincode;
 }

 public String getPincode() {
  return pincode;
 }

 @ManyToOne
 @JoinColumn(name="serviceProvider_id")
 public ServiceProvider getServiceProvider() {
  return serviceProvider;
 }
 public void setServiceProvider(ServiceProvider serviceProvider) {
  this.serviceProvider = serviceProvider;
 }
}

ServiceProvider.java

package com.inception.domain;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;

@Entity
public class ServiceProvider implements Serializable{

 private Long id; 
 private Set<BusinessLocation> businessLocations = new HashSet<BusinessLocation>();

 @Id
 @GeneratedValue
 public Long getId() {
  return id;
 }
 public void setId(Long id) {
  this.id = id;
 }

 @OneToMany(mappedBy="serviceProvider", targetEntity=BusinessLocation.class, cascade=CascadeType.ALL, fetch=FetchType.EAGER)
 public Set<BusinessLocation> getBusinessLocations() {
  return businessLocations;
 }

 public void setBusinessLocations(Set<BusinessLocation> businessLocations) {
  this.businessLocations = businessLocations;
 }

}

**State.java**
package com.inception.domain;

import java.io.Serializable;
import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;

@Entity
public class State implements Serializable {

 private Long id;
 private String name;
 private List<BusinessLocation> businessLocations;

 @Id
 @GeneratedValue 
 public Long getId() {
  return id;
 }
 public void setId(Long id) {
  this.id = id;
 }
 public void setName(String name) {
  this.name = name;
 }

 public String getName() {
  return name;
 }


 @OneToMany(mappedBy="state", targetEntity=BusinessLocation.class, cascade=CascadeType.ALL, fetch=FetchType.EAGER)
 public List<BusinessLocation> getBusinessLocations() {
  return businessLocations;
 }
 public void setBusinessLocations(List<BusinessLocation> businessLocations) {
  this.businessLocations = businessLocations;
 } 

}

StateData.java

package com.inception.domain;

import java.io.Serializable;

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

@Entity
public class StateData implements Serializable{ 

 private Long id;
 private String name;

 @Id
 @GeneratedValue
 public Long getId() {
  return id;
 }
 public void setId(Long id) {
  this.id = id;
 }
 public String getName() {
  return name;
 }
 public void setName(String name) {
  this.name = name;
 }
}

ServiceProviderDAO.java

package com.inception.dao;

import java.util.List;

import com.inception.domain.BusinessLocation;
import com.inception.domain.ServiceProvider;

public interface ServiceProviderDAO {

 public abstract void save(ServiceProvider serviceProvider);
 public abstract List<ServiceProvider> list();
 public abstract void save(BusinessLocation businessLocation);

}

ServiceProviderDAOImpl.java

package com.inception.dao;

import java.util.List;

import org.springframework.orm.hibernate3.HibernateTemplate;

import com.inception.domain.BusinessLocation;
import com.inception.domain.ServiceProvider;

public class ServiceProviderDAOImpl implements ServiceProviderDAO{

 private HibernateTemplate hibernateTemplate;
 public void setHibernateTemplate(HibernateTemplate hibernateTemplate) {
  this.hibernateTemplate = hibernateTemplate;
 }

 public List<ServiceProvider> list() {  
  return hibernateTemplate.find("from ServiceProvider");
 }

 public void save(ServiceProvider serviceProvider) {
  hibernateTemplate.save(serviceProvider);  
 }

 public void save(BusinessLocation businessLocation) {
  hibernateTemplate.save(businessLocation);  
 }

}

ServiceProviderService.java

package com.inception.service;

import java.util.List;

import com.inception.domain.ServiceProvider;

public interface ServiceProviderService {

 public abstract void addServiceProvider(ServiceProvider serviceProvider);
 public abstract List<ServiceProvider> listAllServiceProviders();

}

ServiceProviderServiceImpl.java

package com.inception.service;

import java.util.List;

import org.springframework.transaction.annotation.Transactional;

import com.inception.dao.ServiceProviderDAO;
import com.inception.domain.BusinessLocation;
import com.inception.domain.ServiceProvider;

@Transactional
public class ServiceProviderServiceImpl implements ServiceProviderService{

 private ServiceProviderDAO serviceProviderDAO;
 public void setServiceProviderDAO(ServiceProviderDAO serviceProviderDAO) {
  this.serviceProviderDAO = serviceProviderDAO;
 }

 public void addServiceProvider(ServiceProvider serviceProvider) {
  serviceProviderDAO.save(serviceProvider);

  for(BusinessLocation businessLocation: serviceProvider.getBusinessLocations()) {
   businessLocation.setServiceProvider(serviceProvider);
   serviceProviderDAO.save(businessLocation);
  }

 }

 public List<ServiceProvider> listAllServiceProviders() {
  return serviceProviderDAO.list();
 }

}

numberOfLocationForm.jsp

<%@ page contentType="text/html" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags" %>


<form:form commandName="extendedServiceProvider" method="POST" action="register.htm">
 <input type="hidden" name="page" value="0" /><br>
 Number of locations: <form:input path="locationCount"/><br>
 <input type="submit" name="_target1" value="Next"> 
</form:form>

locationDetailForm.jsp

<%@ page contentType="text/html" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags" %>

currentLocationNumber: ${currentLocationNumber}<br>
locationIndex: ${locationIndex}<br><br>

StateData coming from database: <c:forEach items="${stateData}" var="state" varStatus="status">
 <c:out value="${state.id}" /> - <c:out value="${state.name}" />
 <c:if test="${not status.last}">
  ,
 </c:if>
</c:forEach><br><br>

<form:form commandName="extendedServiceProvider" method="POST" action="register.htm">
 <tr>
  <td>locationCount: <c:out value="${extendedServiceProvider.locationCount}" /></td>
 </tr><br></br>
 <tr>
  <td>Address: </td>
  <td><form:input path="serviceProvider.businessLocations[${locationIndex}].address"/></td>
 </tr><br></br>
 <tr>
  <td>State: </td>
  <td>
   <form:select path="serviceProvider.businessLocations[${locationIndex}].state.id">
    <form:option value="0" label="--Have your pick--" />
    <form:options items="${stateData}" itemValue="id" itemLabel="name" />
   </form:select>
  </td>
 </tr><br></br>
    <input type="submit" name="_target0" value="Back">&nbsp;
    <input type="submit" name="_target1" value="Add Business Location">&nbsp;
    <input type="submit" name="_target2" value="Next">
</form:form>

registrationConfirmationForm.jsp

<%@ page contentType="text/html" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<%@ taglib prefix="spring" uri="http://www.springframework.org/tags" %>

currentLocationNumber: ${currentLocationNumber}<br>
locationIndex: ${locationIndex}<br><br>

Registration confirmation:<hr />

<form:form commandName="extendedServiceProvider" method="POST" action="register.htm">
 <tr>
  <td>locationCount: </td>
  <td><c:out value="${extendedServiceProvider.locationCount}" /></td>
 </tr><br>
 <tr>
  <td>
   <c:forEach items="${extendedServiceProvider.serviceProvider.businessLocations}" var="businessLocation">
    Address: <c:out value="${businessLocation.address}" /><br>
    State: <c:out value="${businessLocation.state.id}" /><br>
   </c:forEach>
  </td>
 </tr>
    <p>Click "Finish" to add service provider.</p>
    <input type="submit" name="_target1" value="Back">&nbsp;<input type="submit" name="_finish" value="Finish">
</form:form><br><br>

home.jsp

Congratulations, you've been redirected to our home page :)

sql code for pre-populating the select tag on locationDetailForm.jsp for mysql

INSERT INTO `statedata` (`id`,`name`) VALUES
 (1,'Alaska'),
 (2,'California'),
 (3,'Delaware'),
 (4,'Florida');

Looking forward to someone waking me up of the blunder i might be committing here. Thanks

Answer 1

Hi

I mistakenly had "serviceProviderDAO" as the parameter variable (line 76 of RegisterServiceProviderController) when I should have had "serviceProviderService". I wonder where did "serviceProviderDAO" come from as i dont remember not using eclipse source creater for getters and setters.

So that NullPointerException thing has been resolved.

Thanks