NullPointerException accurs while trying to call service layer from controller

[rotemya]

I'm working with Spring STS, and creating a spring template project.
(Also with Eclipse-juno, spring 3.1).

My welcome page of the application is a simple form:

      <div id="editPresPage">
         <form action="editPresPage.do" method="post"> 
		<label>Enter Page Text</label><input type="text" name="page_text"/><br>
	    <input type="submit" value="Add New Page"/>
	 </form>		   	  
      </div>

When i deliver the form ,My controller comes into place:

@Controller
@RequestMapping(value = "/")
public class HomeController {
		
	private Page_manager_service page_manager_service;
	
	public void setPage_manager_service(Page_manager_service page_manager_service) {
		this.page_manager_service = page_manager_service;
	}
		
	@RequestMapping(value="/editPresPage",method = RequestMethod.POST)
	public ModelAndView EditPresPage()	  {
		page_manager_service.check();
		
		return new ModelAndView("thanks");		
	}

The controller needs to perform the check method (which is marked) from My Service Layer interface:

public interface Page_manager_service {
	public void check();
}

The Service Layer implementation:

public class Page_manager_service_mock_Impl implements Page_manager_service {

	public void check() {
		System.out.println("check method was done!!!");
	}
}

But i'll getting the following error while executing the check method:

java.lang.NullPointerException
at my.topLevel.pack.HomeController.EditPresPage(HomeC ontroller.java:64)


Here is my servlet-context.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/mvc"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:beans="http://www.springframework.org/schema/beans"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/mvc 
        http://www.springframework.org/schema/mvc/spring-mvc.xsd
	http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring  beans.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

	<!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure -->
	
	<!-- Enables the Spring MVC @Controller programming model -->
	<annotation-driven />

	<!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory -->
	<resources mapping="/resources/**" location="/resources/" />

<!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory -->
	<beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<beans:property name="prefix" value="/WEB-INF/views/" />
		<beans:property name="suffix" value=".jsp" />
	</beans:bean>
	
	<context:component-scan base-package="my.topLevel.pack" />

</beans:beans>

Here is my root-context.xml (you can see that i wired the "page_manager_service" bean):

<?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:context="http://www.springframework.org/schema/context"
	xmlns:jee="http://www.springframework.org/schema/jee"
	xsi:schemaLocation="http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.1.xsd
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd">	
	
	<!-- Root Context: defines shared resources visible to all other web components -->
	<context:annotation-config/> 
	
	<!--  Service Beans -->    
    <bean id="page_manager_service"  class="my.topLevel.pack.Services.Page_manager_service_mock_Impl">
	</bean>	
</beans>

I did not change anything in the web.xml file.

This is how my project looks like - you can see that the service layer implementation is being injected because there is an "s" on it:

mypath.jpg

I Don't know why i'm getting this error..

[Marten Deinum]

I Don't know why i'm getting this error..

How should spring now it should inject the field?! You have a controller, you have service but no configuration or hint for spring that the service must be injected. (I suggest a read of the reference guide). The quick answer add @Autowired to the field.

[rotemya]

Thanks martin, I thought that the "s" sign means that it was injected.

The problem was solved by doing this steps:

First step:Adding @Autowired to the page_manager_service field (It's ok to delete the setter).

Second step: In the root-context.xml file changing:

<context:annotation-config/>

to:

<context:component-scan
base-package="my.topLevel.pack">
</context:component-scan>

Third Step: Removing:

<bean id="page_manager_service" class="my.topLevel.pack.Services.Page_manager_serv ice_mock_Impl">

from root-context.xml.

Fourth Step:Adding @Component to Page_manager_service_mock_Impl