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List traversal is not working in jsp but works fine when I just pass a single element

Time：11-01

Controller code

    @RequestMapping("post/{id}")
    public ModelAndView post(ModelAndView model, @PathVariable Integer id) throws IOException {

        List<Posts> post = postDao.findPostById(id);
        List<Comments> comments = new ArrayList<Comments>();
        comments = (List<Comments>) commentsRepository.findAll();
//      List<Comments> comments = postDao.findAll(id);
        model.addObject("post", post.get(0));
        System.out.println(comments);
        model.addObject("commentsList",comments);
        model.setViewName("Post");

        return model;
    }

JSP code

<div>
            <form class="form-horizontal" action="do_comment" method="POST">
                <textarea rows="2" class="comment-area"></textarea>
                <input type="submit" value="Comment"/>
            </form>
            <c:forEach items="${commentsList}" var="commentsList">
            <div>
                <p>${commentsList.comment}</p><hr><br>
                </div>
            </c:forEach>
        </div>

Comments Class

@Entity
public class Comments {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int commentId;
    private int postId;
    private int userId;
    private String comment;
...

In Console it says NumberFormatException but I am not parsing anything.

Console

Servlet.service() for servlet [jsp] threw exception
    
    java.lang.NumberFormatException: For input string: "comment"
        at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67) ~[na:na]
        at java.base/java.lang.Integer.parseInt(Integer.java:660) ~[na:na]
        at java.base/java.lang.Integer.parseInt(Integer.java:778) ~[na:na]
        at javax.el.ListELResolver.coerce(ListELResolver.java:148) ~[tomcat-embed-el-9.0.54.jar:3.0.FR]
        at javax.el.ListELResolver.getValue(ListELResolver.java:65) ~[tomcat-embed-el-9.0.54.jar:3.0.FR]
        at org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:124) ~[tomcat-jasper-9.0.53.jar:9.0.53]
        at org.apache.el.parser.AstValue.getValue(AstValue.java:168) ~[tomcat-embed-el-9.0.54.jar:9.0.54]
        at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189) ~[tomcat-embed-el-9.0.54.jar:9.0.54]
        at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:692) ~[tomcat-jasper-9.0.53.jar:9.0.53]
        at org.apache.jsp.WEB_002dINF.views.jsp.Post_jsp._jspService(Post_jsp.java:425) ~[na:na]
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70) ~[tomcat-jasper-9.0.53.jar:9.0.53]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.54.jar:4.0.FR]
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:466) ~[tomcat-jasper-9.0.53.jar:9.0.53]
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:379) ~[tomcat-jasper-9.0.53.jar:9.0.53]
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:327) ~[tomcat-jasper-9.0.53.jar:9.0.53]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.54.jar:4.0.FR]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:113) ~[spring-web-5.3.12.jar:5.3.12]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:113) ~[spring-web-5.3.12.jar:5.3.12]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:113) ~[spring-web-5.3.12.jar:5.3.12]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:711) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:459) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:385) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:313) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.springframework.security.web.header.HeaderWriterFilter$HeaderWriterRequestDispatcher.forward(HeaderWriterFilter.java:171) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:171) ~[spring-webmvc-5.3.12.jar:5.3.12]
        at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:316) ~[spring-webmvc-5.3.12.jar:5.3.12]
        at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1400) ~[spring-webmvc-5.3.12.jar:5.3.12]
        at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1145) ~[spring-webmvc-5.3.12.jar:5.3.12]
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1084) ~[spring-webmvc-5.3.12.jar:5.3.12]
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963) ~[spring-webmvc-5.3.12.jar:5.3.12]
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.3.12.jar:5.3.12]
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.3.12.jar:5.3.12]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:655) ~[tomcat-embed-core-9.0.54.jar:4.0.FR]
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.3.12.jar:5.3.12]
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:764) ~[tomcat-embed-core-9.0.54.jar:4.0.FR]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:327) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:115) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:81) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:121) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:115) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:126) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:81) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:105) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:149) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:218) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:212) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:103) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:89) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:117) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.12.jar:5.3.12]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.12.jar:5.3.12]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:110) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:80) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:55) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.12.jar:5.3.12]
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:336) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:211) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:183) ~[spring-security-web-5.5.3.jar:5.5.3]
        at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:358) ~[spring-web-5.3.12.jar:5.3.12]
        at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:271) ~[spring-web-5.3.12.jar:5.3.12]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.3.12.jar:5.3.12]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.12.jar:5.3.12]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.3.12.jar:5.3.12]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.12.jar:5.3.12]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.3.12.jar:5.3.12]
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.3.12.jar:5.3.12]
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:540) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:382) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:895) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1722) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) ~[tomcat-embed-core-9.0.54.jar:9.0.54]
        at java.base/java.lang.Thread.run(Thread.java:831) ~[na:na]

But the same code works when I pass just one element insead of whole list, like this :

    @RequestMapping("post/{id}")
    public ModelAndView post(ModelAndView model, @PathVariable Integer id) throws IOException {

        List<Posts> post = postDao.findPostById(id);
        List<Comments> comments = new ArrayList<Comments>();
        comments = (List<Comments>) commentsRepository.findAll();
//      List<Comments> comments = postDao.findAll(id);
        model.addObject("post", post.get(0));
        System.out.println(comments);
        model.addObject("commentsList",comments.get(0));
        model.setViewName("Post");

        return model;
    }

comment DB

Image of comment database

What should i change here so that this works for the entire list of comments is traversed and displayed? Thanks in advance

CodePudding user response：

You should use another identifier for the var attribute, as commentsList is already used by the list. Example:

<div>
    <form class="form-horizontal" action="do_comment" method="POST">
        <textarea rows="2" class="comment-area"></textarea>
        <input type="submit" value="Comment"/>
    </form>
    <c:forEach items="${commentsList}" var="commentObject">
        <div>
           <p>${commentObject.comment}</p><hr><br>
        </div>
    </c:forEach>
</div>

CodePudding user response：

I added this line and it worked <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

Page link：https//www.codepudding.com/Softwaredesign/174842.html

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