Member Avatar for itsnexgen

Hello Friends,
I am trying to learn JSP, Servlets at the moment.

What am trying to do : A simple text field and a button
What should happen : When you click the button a text should appear something which is specified in the code. for example, "Pradeep".

I am really finding it difficult at the moment to actually bring the JSp and Servlet in connection.

Can anyone help me??

It would be great to start of with a problem to be solved an dthen move ahead.

Thanks and Rgds,
Pradeep (KINO)

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  • Latest Post Latest Post by itsnexgen

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Generated

A short, practical explanation that ties the posts together. is right about the flow: the form posts to a servlet, the servlet supplies the value, and a JSP renders that value. , three small mismatches in the posted code are the likely cause of the empty field.

First, attribute vs parameter: the servlet sets a request attribute, while the JSP reads a request parameter (via request.getParameter). Attributes and parameters are different; when a servlet sets data for a JSP to render, the JSP should read the attribute (or use EL, which checks attributes/scopes automatically). Second, HTML syntax: the value attribute must be quoted — unquoted output can break the markup and make the browser drop the value. Third, forwarding/target: the servlet forwards to whichever JSP should render the form (forward keeps request attributes; a redirect would not).

Minimal examples (use EL in JSP and forward from the servlet):

<input type="text" name="name" value="${name}" />
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
    throws ServletException, IOException {
    req.setAttribute("name", "Pradeep");
    req.getRequestDispatcher("/view.jsp").forward(req, resp); // view.jsp reads ${name}
}

Checklist for debugging:

  • Confirm the servlet mapping matches the form action (use a context-relative path or <c:url>).
  • Inspect the generated HTML (View Source) to see the value="..." actually rendered.
  • Remove if (request==null) checks — request is never null in a JSP.
  • Use server logs (or System.out.println) to verify the servlet runs and sets the attribute.
  • Prefer EL/JSTL over scriptlets for clarity and to avoid null/quoting surprises.

Following those fixes will make the field show "Pradeep" when the button posts to the servlet and the servlet forwards to the JSP.

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All 2 Replies

Member Avatar for jwenting

the button (when activated) submits a post request to the servlet, the servlet sets some information in the http requests and forwards to the JSP.

What part of that don't you get working? It's rather basic...

Member Avatar for itsnexgen

[quote=jwenting;310731]the button (when activated) submits a post request to the servlet, the servlet sets some information in the http requests and forwards to the JSP.

What part of that don't you get working? It's rather basic...[/quote]

Hello Friend,

Index.jsp :

<html>
  <head>
    <title></title>
  </head>
  <body>
    <h2></h2>  
    <form method="post" action="displayname">
      <% String name="";%>
<% if(request==null){
    name="";
}
else{
  name=request.getParameter("name");
}
%>

            Display Name:

            <input type="text" name="name" value=<%=name%> />
<br>
            <input type="submit" name="display" value="Display" />

    </form>
   </body>
</html>

HelloServlet.java

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class HelloServlet extends HttpServlet{

    public void doPost(HttpServletRequest  request, 
                       HttpServletResponse response) 
                  throws ServletException, IOException{

        request.setAttribute("name", "Pradeep");
        getServletContext()
     .getRequestDispatcher("/view.jsp").forward(request, response);
    }
    public void doGet(HttpServletRequest  request, 
                      HttpServletResponse response) 
                  throws ServletException, IOException{
        getServletContext()
     .getRequestDispatcher("/view.jsp").forward(request, response);
    }
}

Any wrong in this code??

please help me try to debug.. Thanks a lot!

KINO

Edited by TrustyTony because: fixed formating
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