<c:out> value attribute not displaying

Question

My JSP (source below) isn't displaying the value attribute of the <c:out> tag. Based on the code below, my ${param.username} is being evaluated correctly. The JSP page is accessed with a request parameter of ?username=jeff.

Any thoughts on why? I feel like I'm missing something simple here.

JSP, output, and source after translation/compilation below:

prac.jsp

<html xmlns:jsp="http://java.sun.com/JSP/Page"
      xmlns:c="http://java.sun.com/jsp/jstl/core">
    <head><title>Practice JSP</title></head>
    <body>
        <h2>Practice JSP</h2>
        Username: <c:out value="${param.username}" default="No username"/><br/>
    </body>   
</html>

Output

Practice JSP
Username:

Source (right click, view page source from browser)

<html xmlns:jsp="http://java.sun.com/JSP/Page"
      xmlns:c="http://java.sun.com/jsp/jstl/core">
    <head><title>Practice JSP</title></head>
    <body>
        <h2>Practice JSP</h2>
        Username: <c:out value="jeff" default="No username"/><br/>
    </body>   
</html>

BalusC BalusC · Accepted Answer · 2013-11-23T13:18:03

Here,

<html xmlns:jsp="http://java.sun.com/JSP/Page"
      xmlns:c="http://java.sun.com/jsp/jstl/core">

you're declaring the taglib as a XML namespace which works only in JSPX, not in "plain vanilla" JSP. Since you didn't explicitly mention "JSPX" anywhere in the question, even not in the file extension, I gather that you're actually using "plain vanilla" JSP. In that case, a XML namespace isn't going to work. You need to declare the taglib by <%@taglib%>.

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

Note that I removed the xmlns:jsp without a @taglib equivalent, as that's already implicitly done by the JSP parser. On contrary to the XML namespace, you don't need to specify the taglib on your own for http://java.sun.com/JSP/Page.

Or, if you actually intend to use JSPX, then you should be renaming the file to prac.jspx.

<c:out> value attribute not displaying

2 Answers

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