Question

I’m working on a web application using Java and its frameworks(Spring 3.1.1). And I’m trying to avoid using scriptlets as much as possible, however I can’t find a way other than this to define an array:

<%
    String[] alphabet = {"A", "B", "C", ... , "Z"};
    pageContext.setAttribute("alphabet", alphabet);      
%> 

After setting pageContext attribute, I can use it with ${alphabet}. But I want to know, is it possible to use plain JSTL/EL to create an array?

UPDATE: I’m using this array to create links. For example, if user clicks ‘S’, a list of employees whose first name starts with ‘S’ comes. So, instead of creating links one by one I’m iterating ${alphabet}.

Answer 1

If you’re already on EL 3.0 (Tomcat 8+, WildFly 8+, GlassFish 4+, Payara 4+, TomEE 7+, etc), which supports new operations on collection objects, you can use ${[...]} syntax to construct a list, and ${{...}} syntax to construct a set.

<c:set var="alphabet" value="${['A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z']}" scope="application" />

If you’re not on EL 3.0 yet, use the ${fn:split()} function trick on a single string which separates the individual characters by a common separator, such as comma.

<c:set var="alphabet" value="${fn:split('A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z', ',')}" scope="application" />

I do however agree that you’re better off using normal Java code for this. Given that it’s apparently static data, just create this listener class:

@WebListener
public class ApplicationData implements ServletContextListener {

    private static final String[] ALPHABET = { "A", "B", "C", ..., "Z" };

    @Override
    public void contextInitialized(ServletContextEvent event) {
        event.getServletContext().setAttribute("alphabet", ALPHABET);
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        // NOOP.
    }

}

It’ll transparently auto-register itself on webapp’s startup and put the desired data in application scope.