Question

i’m trying to pass a List<String[]> object to my jsp page and handle it with jstl.

my servlet:

request.setAttribute("rows", entries);
request.getRequestDispatcher("/pages/result.jsp").forward(request, response);

page:

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
...
${rows}
<c:forEach items="${rows}" var="row">
   <tr>
      <c:forEach items="${row}" var="field">
         <td>${field}</td>
      </c:forEach>
   </tr>
</c:forEach>

the params are not recognized – meaning they are printed as ${rows} and ${field}

the funny thing is that when i do the same using this way (which i understand is bad practice):

<% 
List<String[]> entries = (List<String[]>) request.getAttribute("rows"); 
for...
%>

what am i missing?

Answer 1

meaning they are printed as ${rows} and ${field}

So, EL expressions are not evaluated? That can happen when there’s a version incompatibility between the JSTL version used, the servletcontainer version used and the webapp’s web.xml version.

First you need to figure which Servlet API version is max supported by the target servletcontainer. Then you can determine which JSTL version you actually need and which version the web.xml should be declared to.

Imagine that you’re using Tomcat 7, which is a Servlet 3.0 compatible container, then you should be using at least JSTL 1.2 and the web.xml should be declared conform Servlet 3.0. Or if you’re using Tomcat 6, which is a Servlet 2.5 compatible container, then you should be using at least JSTL 1.1 and the web.xml should be declared conform Servlet 2.5.

A more rare cause, but not uncommon among beginners, is that webapp’s /WEB-INF/lib is incorrectly been cluttered with servletcontainer-specific JAR files such as el-api.jar and so on, which would only conflict the EL installation provided by the target servletcontainer itself.

See also:

• Our JSTL wiki page – contains version/installation details, download links and web.xml examples.