JSTL table creation on JSP Page Load- no data in JSP

Question

I am trying to creating a JSP home page that contains a table of varying sizes. I am wanting to use the forEach JSTL tag. The servlet is working correctly and is producing a list of two products. However this information does not appear on the final HTML.

If I call:

http://localhost:8080/JavaIntoJSP/products

the output is good.

If I call:

http://localhost:8080/JavaIntoJSP/default.jsp

the output is missing

Code as follows (default.jsp):

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

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

<!DOCTYPE html>
<html>
    <head>
        <title>default</title>
    </head>
    <body>  
        <form action="products" method="get">
        <table>
            <c:forEach items="${products}" var="product" >
                <tr> 
                    <td><c:out value="${product.name}" /></td> 
                    <td><c:out value="${product.price}" /></td>
                    <td><c:out value="${product.category}" /></td>
                    <td><c:out value="${product.units}" /></td> 
                </tr>
            </c:forEach>
        </table>
        </form>
        <h1>try again</h1>

    </body>
</html>

The Servlet has the following

@WebServlet("/products")
public class ProductServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public ProductServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        List<Product> products = new ArrayList<Product>();
        Product prod1   = new Product();
        prod1 = prod1.returnProduct();
        products.add(prod1);
        Product prod2   = new Product();
        prod2 = prod2.returnProduct();
        prod2 = prod2.returnProduct();
        products.add(prod2);


        request.setAttribute("products", products);
        request.getRequestDispatcher("default.jsp").forward(request, response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
    }    
}

Can anyone plese let me know why the products are not being found on the JSP?

What's the URL displayed in your browser's address bar when trying to display the page? — JB Nizet, Jan 27 '14 at 14:08

score 2 · Accepted Answer · edited May 23 '17 at 12:21

http://localhost:8080/JavaIntoJSP/products

It calls the ProductServlet where products list is filled and forwarded to default.jsp

http://localhost:8080/JavaIntoJSP/default.jsp

If you call default.jsp directly then products list will be null & because of that you can not see any out put on the screen.

Update

Answer to your question from comment

Do not write scriptlets <% %> in JSP, because scriptlets shouldn't be used in JSPs for more than a decade. Learn the JSP EL, the JSTL, and use servlet for the Java code. How to avoid Java Code in JSP-Files?

Use empty operator to check products list is null and empty. There is not if-else in EL, so you have to use <c:choose><c:when>...

<c:choose>
  <c:when test="${!empty products}">
     //print the list 
  </c:when>
  <c:otherwise>
     //call the servlet
    <jsp:forward page="products"></jsp:forward> 
  </c:otherwise>
</c:choose>

Thanks to Aniket and AdolAurion. The problem was that I was not making a call to the Servlet from the default.jsp I have since modified my code to include a conditional call to the servlet. If anyone knows a cleaner way to do this I would be glad to hear. <% if (request.getAttribute("products") == null){ %> <% } %> — opc51, Jan 28 '14 at 08:51

score 0 · Answer 2 · answered Jan 27 '14 at 14:29

0

http://localhost:8080/JavaIntoJSP/default.jsp doesnt call the servlet. Therefore you wont get "products" into your request's attributes.

You should check on "default.jsp" whether "products" is available.

answered Jan 27 '14 at 14:29

agastalver

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JSTL table creation on JSP Page Load- no data in JSP

2 Answers2

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