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

[Rohit Bhal]

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">
						
	<!-- 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"> 
    <input type="submit" name="_target1" value="Add Business Location"> 
    <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"> <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

[David Newton]

There's like 600 lines of code there. Would it be possible for you to post a minimal use case that demonstrates the problem more concisely?

[Rohit Bhal]

Hello David

I've tried to compile the problem I've been having in an another post below:
https://coderanch.com/t/507689/Spring/AbstractWizardFormController-teasing-command-object

Thanks for the reply

[Rohit Bhal]

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

[David Newton]

Glad to hear to worked it out--errors like that can be hard to find!