Servlet send arraylist to JSP as request attribute

Question

I am attempting to send an ArrayList from a servlet to a JSP page. In the Servlet:

List<ItemObj> myList = new ArrayList<ItemObj>();   
req.setAttribute("list", myList);
req.getRequestDispatcher("page.jsp").forward(req,resp);

In the JSP:

<% List<ItemObj> myList = (ArrayList<ItemObj>) request.getParameter("list"); %>

However, I keep getting an error: Cannot cast from String to List. I have found sources that indicate that I can cast as such:

What am I doing wrong?

great catch, apologies. I am new to JSP and still trying to get a good understanding of the difference between the two. Thank you! — Nathaniel Wendt, Mar 15 '14 at 04:10
It is highly discouraged, for reasons explained [here](http://www.oracle.com/technetwork/articles/javase/code-convention-138726.html). — Sotirios Delimanolis, Mar 15 '14 at 04:14
@thepristinedesign plz close the question if u got ur answer.. — Santino 'Sonny' Corleone, Mar 15 '14 at 05:14

score 1 · Answer 1 · answered Mar 15 '14 at 04:09

1

Instead of request.getParameter use

<% List<ItemObj> myList = (ArrayList<ItemObj>) request.getAttribute("list"); %>

request.getParameter is used to retrieve form parameters.

answered Mar 15 '14 at 04:09

score 1 · Accepted Answer · answered Mar 15 '14 at 04:09

1

You are setting list as request attribute and getting it back as request parameter

Use <% List<ItemObj> myList = (ArrayList<ItemObj>) request.getAttribute("list"); %>

answered Mar 15 '14 at 04:09

Keerthivasan

score 1 · Answer 3 · answered Mar 15 '14 at 04:09

1

Sotirious is spot-on. You need to call getAttribute.

But beyond that, you should be privy to the scope of your attribute: is it scoped to (i) page, (ii) request, (iii) session, or (iv) application?

I don't know the default scope off-hand, but you might want to look into that.

answered Mar 15 '14 at 04:09

Kode Charlie

I am intending here for page scope. I'm guessing that attribute is a poor choice then? – Nathaniel Wendt Mar 15 '14 at 04:12
I think setAttribute is the right call. Just make sure your scope is right. – Kode Charlie Mar 15 '14 at 04:24

score 0 · Answer 4 · answered Mar 15 '14 at 04:11

0

You need request.getAttribute() instead of request.getParameter()

answered Mar 15 '14 at 04:11

Sagar Sane

4 Answers4