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POException java.lang.NullPointerException accurs while trying to reach the service layer from my controller
 

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  1. POException java.lang.NullPointerException accurs while trying to reach the service layer from my controller
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    <p>I'm working with Spring STS (Also with Eclipse-juno, spring 3.1), and creating a spring template project.</p> <p>My welcome page of the application is a simple form:</p> <pre><code> &lt;div id="editPresPage"&gt; &lt;form action="editPresPage.do" method="post"&gt; &lt;label&gt;Enter Page Text&lt;/label&gt;&lt;input type="text" name="page_text"/&gt;&lt;br&gt; &lt;input type="submit" value="Add New Page"/&gt; &lt;/form&gt; &lt;/div&gt; </code></pre> <p>When i deliver the form ,My controller comes into place:</p> <pre><code>@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"); } </code></pre> <p>The controller needs to perform the check method (which is marked) from My Service Layer interface:</p> <pre><code>public interface Page_manager_service { public void check(); } </code></pre> <p>The Service Layer implementation:</p> <pre><code>public class Page_manager_service_mock_Impl implements Page_manager_service { public void check() { System.out.println("check method was done!!!"); } } </code></pre> <p>But i'll getting the following error while executing the check method:</p> <p><em><strong>java.lang.NullPointerException at my.topLevel.pack.HomeController.EditPresPage(HomeController.java:64)</em></strong> </p> <p>Here is my servlet-context.xml:</p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;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"&gt; &lt;!-- DispatcherServlet Context: defines this servlet's request-processing infrastructure --&gt; &lt;!-- Enables the Spring MVC @Controller programming model --&gt; &lt;annotation-driven /&gt; &lt;!-- Handles HTTP GET requests for /resources/** by efficiently serving up static resources in the ${webappRoot}/resources directory --&gt; &lt;resources mapping="/resources/**" location="/resources/" /&gt; &lt;!-- Resolves views selected for rendering by @Controllers to .jsp resources in the /WEB-INF/views directory --&gt; &lt;beans:bean class="org.springframework.web.servlet.view.InternalResourceViewResolver"&gt; &lt;beans:property name="prefix" value="/WEB-INF/views/" /&gt; &lt;beans:property name="suffix" value=".jsp" /&gt; &lt;/beans:bean&gt; &lt;context:component-scan base-package="my.topLevel.pack" /&gt; &lt;/beans:beans&gt; </code></pre> <p>Here is my root-context.xml (you can see that i wired the "page_manager_service" bean):</p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;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"&gt; &lt;!-- Root Context: defines shared resources visible to all other web components --&gt; &lt;context:annotation-config/&gt; &lt;!-- Service Beans --&gt; &lt;bean id="page_manager_service" class="my.topLevel.pack.Services.Page_manager_service_mock_Impl"&gt; &lt;/bean&gt; &lt;/beans&gt; </code></pre> <p>I did not change anything in the web.xml file.</p> <p>I can see that the service layer implementation is being injected because there is an "s" on it.</p> <p>I'm able to transfer parameters from the view to the controller- so the problem isn't there.</p> <p>It's in the controller&lt;-> service layer communication.</p> <p>I Don't know why i'm getting this error..</p> <p>The problem was solved by doing this steps:</p> <p>First step:Adding @Autowired to the page_manager_service field (It's ok to delete the setter).</p> <p>Second step: In the root-context.xml file changing:</p> <pre><code>&lt;context:annotation-config/&gt; </code></pre> <p>to:</p> <pre><code>&lt;context:component-scan base-package="my.topLevel.pack"&gt; &lt;/context:component-scan&gt; </code></pre> <p>Third Step: Removing: </p> <pre><code>&lt;bean id="page_manager_service" class="my.topLevel.pack.Services.Page_manager_service_mock_Impl"&gt; </code></pre> <p>from root-context.xml.</p> <p>Fourth Step:Adding @Component to Page_manager_service_mock_Impl</p>
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    1. USRotemya
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      1. VTUpMod
    1. COUr Service bean has not been injected and its not available when the control comes to that point.Hence NullPointerException. I dont see where you have mapped the Service Bean to the controller Bean.
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      1. USmavrav
 

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