Question

Using JSTL’s forEach tag, is it possible to iterate in reverse order?

Answer 1

When you are using forEach to create an integer loop, you can go forward or backward, but it requires some work. It turns out you cannot do this, for example:

<c:forEach var='i' begin='10' end='0' step='-1'>     .... </c:forEach> 

because the spec requires the step is positive. But you can always loop in forward order and then use <c:var to convert the incrementing number into a decrementing number:

<c:forEach var='i' begin='0' end='10' step='1'>    <c:var var='decr' value='${10-i}'/>     .... </c:forEach> 

However, when you are doing a forEach over a Collection of any sort, I am not aware of any way to have the objects in reverse order. At least, not without first sorting the elements into reverse order and then using forEach.

I have successfully navigated a forEach loop in a desired order by doing something like the following in a JSP:

<% List list = (List)session.getAttribute('list'); Comparator comp = .... Collections.sort(list, comp); %>   <c:forEach var='bean' items='<%=list%>'>      ... </c:forEach> 

With a suitable Comparator, you can loop over the items in any desired order. This works. But I am not aware of a way to say, very simply, iterate in reverse order the collection provided.