Getting NumberFormatException due to usage of wrong EL syntax

[karthik chellappan]

I've a dropdown where i'm trying to display the dropdown values using EL in a c:forEach Loop as shown below :

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
...
<td>Category</td>
		<td><select name="category">
			<c:forEach items="${categoryList}" var="category" >
				<option value="${category.catId}">
				${category.name}</option>
			</c:forEach>
		</select></td>

In the above code, category is a bean class which has following fields:

private int catId;
private String name;
private String description;

I'm getting the selected dropdown value in controller servlet as shown below :

int catId=Integer.parseInt(request.getParameter("category")); // i'm getting java.lang.NumberFormatException: For input string: "${category.catId}" at this line.

When i printed the above line i.e.

System.out.println("request.getParameter(category)::"+request.getParameter("category"));

i got :

request.getParameter(category)::${category.catId}

instead of selected catID value, which means EL syntax which i'm using to access the catID from category object is wrong.
i tried using the following syntax

<c:forEach items="${requestScope.categoryList}" var="category" >

& by removing "" around EL in 'value' attribute,but both of them didnt work.
Can any one please let me know what is correct usage here?

[Rob Spoor]

I don't see anything wrong with your syntax. Are you sure that EL is enabled? If you have a web.xml that is specified to use the Servlet 2.3 spec, then EL is disabled by default.

[karthik chellappan]

Rob,

Servlet version i had was : 2.4
JSP version : 2.0
Server : Apache Tomcat/5.5.27

I saw following in web.xml of the above application:
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">

when i created new web application, the default declaration was of version 2.4 i.e.
<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

I used the above line of code in place of existing code in web.xml and it worked. Thanks for the reply.

[Rob Spoor]

That version 2.5 should have worked, unless your servlet container (Tomcat?) doesn't support it. Which container do you use?

[karthik chellappan]

Rob,

I'm using Apache Tomcat/5.5.27.

[Bear Bibeault]

Just look at the code at the browser with view source. Has the EL been evaluated? If not, that's the problem you need to solve.

[karthik chellappan]

Bear,

I just changed my root declaration in web.xml to version 2.5 and for my surprise, it worked perfectly fine. I checked source in the browser and saw that EL was evaluated properly which was not happening earlier for version 2.5. When i changed to 2.4 version i didn't get exception (it worked fine) and now i'm not getting exception in 2.5 version as well. So i'm quite confused and not sure why i was getting initially this error.

[karthik chellappan]

I was encountering this problem intermittently and on googling i got below link where they say it could be a bug in Tomcat.

EL

So to avoid this problem i have to include

<%@ page isELIgnored="false" %>

in jsp page or add <el-ignored>false</el-ignored> in web.xml even though EL is enabled by default for Servlet 2.4 spec and above.

[Bear Bibeault]

You should never have to put anything on the pages to enable the EL.