Spring - java.lang.NumberFormatException: For input string - spring

Question

I'm trying to get a list of users and their associated objects using a DTO. So far there is an error.
Model
public class UserEntity
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="setter")
private Set<Module> sModule = new HashSet<Module>();
#OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="checker")
private Set<Module> cModule = new HashSet<Module>();
//getters and setters
DTO
public class UserEntityDTO {
private List<Module> sModule = new ArrayList<Module>();
private List<Module> cModule = new ArrayList<Module>();
Controller
#RequestMapping(value = "/main/user/testing", method = RequestMethod.GET)
public String getRecords(Model model) {
List<UserEntity> users = userService.getUserEntity();
List<UserEntityDTO> usersDTO = new ArrayList<UserEntityDTO>();
for (UserEntity user: users) {
UserEntityDTO dto = new UserEntityDTO();
dto.setUserId(user.getUserId());
dto.setName(user.getName());
dto.setsModule(moduleService.getSetterModules(user.getUserId()));
dto.setcModule(moduleService.getCheckerModules(user.getUserId()));
usersDTO.add(dto);
}
model.addAttribute("users", usersDTO);
return "/main/user/testing";
}
JSP page
<table>
<tr>
<th>User Id</th>
<th>User Name</th>
<th>Module</th>
</tr>
<c:forEach items="${users}" var="setter" >
<c:forEach items="${users.sModule}" var="module" >
<tr>
<td><c:out value="${setter.userId}" escapeXml="true" /></td>
<td><c:out value="${setter.name}" escapeXml="true" /></td>
<td><c:out value="${module.moduleCode}" escapeXml="true" /></td>
<td><c:out value="${module.moduleName}" escapeXml="true" /></td>
<td><c:out value="${module.moduleStatus}" escapeXml="true" /></td>
</tr>
</c:forEach>
</c:forEach>
</table>
The stacktrace
java.lang.NumberFormatException: For input string: "sModule"
java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
java.lang.Integer.parseInt(Integer.java:492)
java.lang.Integer.parseInt(Integer.java:527)
javax.el.ListELResolver.coerce(ListELResolver.java:173)
javax.el.ListELResolver.getValue(ListELResolver.java:52)
org.apache.jasper.el.JasperELResolver.getValue(JasperELResolver.java:104)
org.apache.el.parser.AstValue.getValue(AstValue.java:183)
org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:185)
org.apache.jasper.el.JspValueExpression.getValue(JspValueExpression.java:106)
org.apache.jsp.WEB_002dINF.views.main.user.testing_jsp._jspx_meth_c_005fforEach_005f1(testing_jsp.java:204)
org.apache.jsp.WEB_002dINF.views.main.user.testing_jsp._jspx_meth_c_005fforEach_005f0(testing_jsp.java:172)
org.apache.jsp.WEB_002dINF.views.main.user.testing_jsp._jspService(testing_jsp.java:111)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.springframework.web.servlet.view.InternalResourceView.renderMergedOutputModel(InternalResourceView.java:238)
org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:264)
org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1208)
org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:992)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:939)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:915)
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:811)
javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:796)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.access.channel.ChannelProcessingFilter.doFilter(ChannelProcessingFilter.java:144)
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
It is taking an exception at the child objects I want to retrieve. How can I make sure that the field I want to get can be accepted.

Answer 1

You're accessing modules in your jsp in the wrong way.
This:
<c:forEach items="${users}" var="setter" >
<c:forEach items="${users.sModule}" var="module" >
tries to access sModule member of users, and since users is a list it tries to convert sModule to integer and use that as an index.
It should probably be:
<c:forEach items="${users}" var="user" >
<c:forEach items="${user.sModule}" var="module" >