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Can I access the values of an enum class from a JSP using EL?
Asked Answered
javajspjstlenumsel
J

3

8

I have an enum class USState. I would like to iterate through the states in a JSP.

Is it possible to access a list of USStates without first setting such a list as an attribute? It seems that something as static as an enum should always be available, but I can't figure out how to do it.

Here's what I'm looking for: (except working)

<c:forEach var="state" items="${USState.values}" >
    <option value="${state}">${state}</option>
</c:forEach>
Janeyjangle answered 10/2, 2010 at 22:9 Comment(2)
#2237635 Shouldn't you be grabbing Struts? :) – Downwards
I think that's what I'll do. I'm building something small, and the initial thought was that Struts wouldn't be necessary. – Janeyjangle
S
9

You will have to create a list somewhere on your backing code and pass it as a model parameter. Preferably in an ServletContextListener (as advised by BalusC) and put it in the ServletContext (i.e. application scope):

servletContext.setAttribute("statesList", YourEnum.values());
Smythe answered 10/2, 2010 at 22:21 Comment(5)
As it's already a constant I'd just put it in application scope, if necessary with help of ServletContextListener. Another alternative is a custom EL resolver or EL function, but that's a bit of work. – Downwards
@BalusC: I've started to do this already. I started to think I must be hacking around the correct approach. – Janeyjangle
I'm pretty sure that there is no need for the Arrays.asList() call. You can just do servletContext.setAttribute("statesList", YourEnum.values()); – Chitkara
@Matt Ball - agreed. Fixing it. – Smythe
Anyway, +1 for application scoping with a ServletContextListener. – Chitkara
D
9

You can also consider to wrap it in a Javabean like follows:

package com.stackoverflow.q2240722;

public class StateBean {

    public State[] getValues() {
        return State.values();
    }

}

This way it's accessible by <jsp:useBean>:

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

<jsp:useBean id="stateBean" class="com.stackoverflow.q2240722.StateBean" />

<!doctype html>
<html lang="en">
    <head>
        <title>SO question 2240722</title>
    </head>
    <body>
        <select>
            <c:forEach items="${stateBean.values}" var="state">
                <option value="${state}">${state}</option>        
            </c:forEach>
        </select>
    </body>
</html>
Downwards answered 10/2, 2010 at 22:54 Comment(0)
C
7

Note that you can also use a scriptlet (I don't think it's too harmful in such a simple case):

<c:forEach var="state" items="<%= USState.values() %>" >

(USState should be either fully qualified or imported using <%@ page import = "..." %>

Christensen answered 10/2, 2010 at 22:40 Comment(2)
This is the current state of my code. It works, but I thought I must be missing the easier way. – Janeyjangle
My personal opinion is that this is more maintainable than the other solutions. It's short and you don't have to rely on strings that can change and break without you noticing. In this instance I won't run away from scriptlets. – Disturb

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