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POHow to get Dynamic Drop Down Box in JSP
 

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  1. POHow to get Dynamic Drop Down Box in JSP
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    <p>I want to populate a dropdown box in Spring MVC i tried to do this but i am getting null pointer exception </p> <p>this is my controller:</p> <pre><code>public class CatalogueController { private CatalogueService catalogueService; private PublisherService publisherService; private SubjectService subjectService; // some code and i generated setter and getter methods ............ @RequestMapping(value="/catalogue/new.action", method=RequestMethod.GET) public ModelAndView newMember() throws Exception { ModelAndView mvc= null; mvc = new ModelAndView("catalogue/catalogueForm", "catalogueForm", new CatalogueBase()); mvc.addObject("copyDetailForm", new CatalogueCopyDetails()); List&lt;Publisher&gt; publist = publisherService.getPublisherList(); mvc.addObject("publist", publist); List&lt;Subject&gt; subjectlist = subjectService.getSubjectList(); mvc.addObject("subjectlist", subjectlist); return mvc; } </code></pre> <p>this is my service method :</p> <pre><code> @Override public List&lt;Publisher&gt; getPublisherList() { List&lt;Publisher&gt; list = publisherDAO.getPublisher(); return list; } @Override public List&lt;Subject&gt; getSubjectList() { List&lt;Subject&gt; list = subjectDAO.getSubjects(); return list; } </code></pre> <p>this is my DAO Method:</p> <pre><code> @SuppressWarnings("unchecked") public List&lt;Publisher&gt; getPublisher() { Query qry = getSession().createQuery("from Publisher"); return qry.list(); } @SuppressWarnings("unchecked") public List&lt;Subject&gt; getSubjects() { Query qry = getSession().createQuery("from Subject"); return qry.list(); } </code></pre> <p>finally this is my JSP page :</p> <pre><code> &lt;form:form commandname="catalogueForm" action="${pageContext.request.contextPath}/catalogue/create.action" method="post" modelAttribute="catalogueForm"&gt; &lt;form:select path="publisher.id" id="publisher.id"&gt; &lt;form:options items="${publist}" itemValue="id" itemLabel="name" /&gt; &lt;/form:select&gt; &lt;form:select path="subject.id" id="subject.id"&gt; &lt;form:options items="${subjectlist}" itemValue="id" itemLabel="name" /&gt; &lt;/form:select&gt; &lt;/form:form&gt; </code></pre> <p>This is Stack Trace:</p> <p>java.lang.NullPointerException at com.easylib.elibrary.webapp.controller.catalogue.CatalogueController.newMember(CatalogueController.java:80) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:601) at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:100) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:604) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:565) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)</p>
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