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Asked: 2026-05-20T10:47:31+00:00

Good day! I encountered the following error upon running my JSP program. java.lang.IllegalStateException: PWC3991:

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Good day!

I encountered the following error upon running my JSP program.

java.lang.IllegalStateException: PWC3991: getOutputStream() has already been called for this response

It seems like the html file inside my JSP doesn’t work.
My code is as follows:

<%@page import  = "java.util.*"%>
<%@page import  = "javax.servlet.*"%>
<%@page import  = "javax.servlet.http.*"%>
<%@page import= "session.*" %>


<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">

    <html>
        <head>
            <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
            <title>JSP Page</title>
        </head>
        <body>
            <%
            Item item = (Item) request.getAttribute("invenItem");

            if (item != null) {
                out.println("<html><title>Inventory Item</title>");
                out.println("<body><h1>Inventory Item Details:</h1>");
                out.println("Stock ID  : " + item.getStockID() + "<br/>");
                out.println("Name      : " + item.getItemName() + "<br/>");
                out.println("Unit Price: " + item.getUnitPrice() + "<br/>");
                out.println("On Stock  : " + item.getOnStock() + "<br/>");
                out.println("</body>");
                out.println("</html>");
            } else {
                RequestDispatcher rd = request.getRequestDispatcher("DataForm.html"); //NOT WORKING
                rd.include(request, response);

                out.println("<br>Item not found...<br>");

                rd = request.getRequestDispatcher("ItemEntry.html"); //NOT WORKING
                rd.include(request, response);
            }
            %>
        </body>
    </html>

My html Files are located inside the folder WEB-INF. How can I make it work? DO i need to import it also? Thank you.

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1 Answer

  1. Editorial Team

    Don’t use scriptlets (those <% %> things). JSP is a template technology for HTML. You don’t need all those nasty out.println() things for HTML. Just write HTML plain in JSP.

    So, instead of

    <%
    out.println("<html><title>Inventory Item</title>");
%>

    just do

    <html><title>Inventory Item</title>

    (note that this results in invalid HTML, there should be only one <html> tag in a HTML page and only one <title> in the <head>, but that’s a different problem, the w3 HTML validator should give a lot of hints and answers, also get yourself through some HTML tutorials)

    JSP offers EL (Expression Language, those ${ } things) to access backend data, i.e. the data which is present as attribute in page, request, session and application scopes. It can be accessed using the attribute name.

    So, instead of

    <%
    Item item = (Item) request.getAttribute("invenItem");
%>

    use

    ${invenItem}

    and instead of

    <%
    out.println("Stock ID  : " + item.getStockID() + "<br/>");
%>

    use

    Stock ID: ${invenItem.stockID}<br/>

    JSP also offers taglibs like JSTL to control the page flow and output.

    So, instead of

    <%
    if (item != null) {

    } else {

    }
%>

    use

    <c:choose>
    <c:when test="${invenItem != null}">

    </c:when>
    <c:otherwise>

    </c:otherwise>
</c:choose>

    JSP also offers <jsp:include> tag to include page fragments.

    So, instead of

    <%
    RequestDispatcher rd = request.getRequestDispatcher("DataForm.html"); //NOT WORKING
    rd.include(request, response);
%>

    use

    <jsp:include page="/WEB-INF/DataForm.jsp" />

    (and rename it to .jsp)

    And the exception will disappear.

    See also:

    Unrelated to the concrete problem, almost all of the links in this answer was already (in)directly given to you in your previous questions. Take them serious. To become a great programmer (as you ever stated in a question/comment), take some time to get yourself through those links (and the links in the links).

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