${fn:length ()} throws javax.servlet.ServletException:

Question

This is an Issue with JSTL in struts framework
a.class
private StringBuilder actionPlans;
b.jsp
<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn"%>
<c:choose>
                                                                 <c:when test="${empty summaryCO.actionPlans}">
                                                                      <c:out value="${summaryCO.actionPlans}"/>
                                                                 </c:when>
                                                                 <c:otherwise>
                                                                      <c:out value="${summaryCO.actionPlans}"/>
                                                                      <c:out value="${fn:length(summaryCO.actionPlans)}"/>
                                                                      <html:link page="/maintainSummaryPre.do?method=readSummaryAction&&actionPlanDesc=${summaryCO.actionPlans}" styleClass="ajaxOverlayTrigger">
                                                                      <fmt:message key="label.viewSummary.readSummaryActionPlan"/>
                                                                      </html:link>
                                                                 </c:otherwise>
                                                       </c:choose>
In the above piece of code fn:length is not fetching result and throws
javax.servlet.ServletException: An error occurred while evaluating function "fn:length"
but when is use ${fn:toUpperCase , it workd fine and fetches me correct result ..
please reply why it throws error only for length . my requirement is to find the length of that String and display it .
do we have any other alternative in JSTL or struts to do this..
Thanks                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

Answer 1

<c:out value="${fn:length(summaryForm.currentRedRatedDeliverablesByCategory)}"/>
<c:forEach var="summaryCO" items="${summaryForm.currentRedRatedDeliverablesByCategory}">
<tr>
<td>
<c:set var="actionPlanString" value="${summaryCO.actionPlans}"></c:set>
     <c:choose>
     <c:when test="${empty summaryCO.actionPlans}">
     <c:out value="${summaryCO.actionPlans}"/>
     </c:when>                                         <c:otherwise>
     <c:out value="${summaryCO.actionPlans}"/>
<c:out value="${fn:length(actionPlanString)}"/>
          <html:link page="/maintainSummaryPre.do?
method=readSummaryAction&&actionPlanDesc=${summaryCO.actionPlans}"
styleClass="ajaxOverlayTrigger">
          <fmt:message key="label.viewSummary.readSummaryActionPlan"/>
          </html:link>
     </c:otherwise>
</c:choose>
</td>
</tr>                                   
</c:forEach>
In this piece of code the first line gives the length value of the ArraList
so fn:length works fine for getting the no of chars of a list .
but inside the list when i use <c:out value="${fn:length(actionPlanString)}"/> to get the length of a String of an item in the ArrayList
it didnt fetch the count , it throws
javax.servlet.jsp.JspTagException: Don't know how to iterate over supplied "items" in &lt;forEach&gt;
     at org.apache.taglibs.standard.functions.Functions.length(Unknown Source)
javax.servlet.ServletException: An error occurred while evaluating function "fn:length"
The Issues assumptions are following
1) becoz it is a stringbuilder and fn:length does not work for that
2)as the String builder is set to var it is converted to a string and still fn:length does not work becoz it is and item inside the List
3)fn:length cant be used for getting the length of the string as it will work only if a string is outside a loop.
ultimately my requirement is to print the no of characters of the "actionPlanString" which is inside the loop of List.
I need an answer with a modified code piece .
Thanks.