Using for loop inside of a JSP

Question

I want to loop through an ArrayList of "Festivals" and get their information with get methods, printing out all its values. For some reason when I use this code, it will always choose the "0"th value and not increment the loop.

If I hard code the values as "get(1)" it will get the correct values so my issue is clearly with the syntax.

<h1>All Festival Information</h1>     <jsp:useBean id="allFestivals" type="java.util.ArrayList" scope="session" />     <table border="1">         <tr>             <td>Festival Name:</td>             <td>Location:</td>             <td>Start Date:</td>             <td>End Date:</td>             <td>URL:</td>         </tr>         <% for(int i = 0; i < allFestivals.size(); i+=1) { %>             <tr>                       <td>${allFestivals.get(i).getFestivalName()}</td>                 <td>${allFestivals.get(i).getLocation()}</td>                 <td>${allFestivals.get(i).getStartDate()}</td>                 <td>${allFestivals.get(i).getEndDate()}</td>                 <td>${allFestivals.get(i).getURL()}</td>               </tr>         <% } %>     </table>  

Answer 1

You concrete problem is caused because you're mixing discouraged and old school scriptlets <% %> with its successor EL ${}. They do not share the same variable scope. The allFestivals is not available in scriptlet scope and the i is not available in EL scope.

You should install JSTL (<-- click the link for instructions) and declare it in top of JSP as follows:

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> 

and then iterate over the list as follows:

<c:forEach items="${allFestivals}" var="festival">     <tr>               <td>${festival.festivalName}</td>         <td>${festival.location}</td>         <td>${festival.startDate}</td>         <td>${festival.endDate}</td>         <td>${festival.URL}</td>       </tr> </c:forEach> 

(beware of possible XSS attack holes, use <c:out> accordingly)

Don't forget to remove the <jsp:useBean> as it has no utter value here when you're using a servlet as model-and-view controller. It would only lead to confusion. See also our servlets wiki page. Further you would do yourself a favour to disable scriptlets by the following entry in web.xml so that you won't accidently use them:

<jsp-config>     <jsp-property-group>         <url-pattern>*.jsp</url-pattern>         <scripting-invalid>true</scripting-invalid>     </jsp-property-group> </jsp-config>