How can I sort an array with JSTL?

Question

For example if a have this:

<form method="post">
    <c:forEach var = "i" begin = "0" end = "5">
        <input type="text" name="textbox">
    </c:forEach>
    <button type="submit" name="buttonSave">Save</button>
</form>
<c:set var="data" value="${paramValues.textbox}"/>
<c:forEach var = "item"  items="${data}">
    ${item}
</c:forEach>

How can I sort my array?, using JSTL if it's possible.

Can you not sort the array before you send it the JSP? (i.e. on the backend) — blurfus, Aug 08 '22 at 22:39
@blurfus Yes, but I'm not using backend :(, and I think that's the best solution but I've to do it for school. — Raúl Peñate, Aug 08 '22 at 22:41
If you don't want to use a scriptlet, then you should use a "custom EL function". — rickz, Aug 09 '22 at 01:25

score 1 · Answer 1 · answered Aug 09 '22 at 00:44

Did you put the taglib on the top of jsp?

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

Actually it's fine to put one (1)

but usually we put the other together

like this

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

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

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

score 1 · Accepted Answer · answered Aug 09 '22 at 04:43

I don't think there's JSTL support for sorting of array or of collection. You either create your own custom tag to sort or you can just write Java code to perform the sort before processing it. See example below:

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
  <body>
    <form action="index.jsp" method="post">
      <input type="text" name="items"><br>
      <input type="text" name="items"><br>
      <input type="text" name="items"><br>
      <input type="text" name="items"><br>
      <input type="submit" name="submit" value="submit">
    </form>
    <% String[] input = request.getParameterValues("items");
       if (input != null) {
          java.util.Arrays.sort(input);
          request.setAttribute("items", input);
       }
    %>
    <c:forEach var="item" items="${items}">
      <div>${item}</div>
    </c:forEach>
  </body>

How can I sort an array with JSTL?

2 Answers2