Hi every body, I tried to search for my own problem, I would think this must be popular issue but unfortunately I found no solution in Google.

I tried to use (boolean) session.getAttribute("IsValidUser") to get the attribute of Session, but that caused error:

org.apache.jasper.JasperException: PWC6033: Error in Javac compilation for JSP

PWC6197: An error occurred at line: 8 in the jsp file: /WEB-INF/jsp/index.jsp
PWC6199: Generated servlet error:
inconvertible types
  required: boolean
  found:    java.lang.Object

So below is my JSP code:

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@page session="true" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
    "http://www.w3.org/TR/html4/loose.dtd">
<%! boolean IsValidUser = false ; %>
<%   int LoginTriesTime = 0 ;%>
<%   String UserName = "" ;%>
<%
    try
    {
        IsValidUser = (boolean) session.getAttribute("IsValidUser") ; //THIS IS WHERE THE ERROR CAUSED
    }
    catch (IllegalStateException Ex)
    {
        Ex.printStackTrace();
    }

    if (IsValidUser == true)
    {
        UserName = (String) session.getAttribute("UserName");
    }
    else
    {
        LoginTriesTime = (int) session.getAttribute("LoginTryTimes"); //THIS IS WHERE THE ERROR CAUSED
    }
%>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>Welcome to Spring Web MVC project</title>
    </head>

    <body>
<%
    if (IsValidUser == true)
    {
%>
        <h3>Welcome <%= UserName %></h3>
<%
    }
    else
    {
        response.sendRedirect("login.jsp");
    }
%>

    </body>
</html>

Really appreciate if you guys can help me figure out this. I'm new to JSP

Many Thanks,
Tu Dinh

Use Boolean not boolean.

WOW that looks so simple and makes sense, an Object instead of primitive type.
I will try tonight.

@masijade Thank you so much!