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Check session on a Java code

Greenhorn

Posts: 15

posted 10 years ago

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Hi,

In my system, I'm trying to check the session status via a java method. But it gave me an NullPointerException. So I've reduced some code to find the error but I couldn't able to find it. Further the same code with some alteration will work perfectly in JSP page.

My JSP Page

My SessionCheck Java Class

This is the error

HTTP Status 500 - An exception occurred processing JSP page /newjsp.jsp at line 22

type Exception report

message An exception occurred processing JSP page /newjsp.jsp at line 22

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: An exception occurred processing JSP page /newjsp.jsp at line 22

19: <%
20: session.setAttribute("status", "Test");
21: SessionCheck sc = new SessionCheck();
22: boolean sesVal = sc.sesCheck();
23:
24: %>
25: </body>

Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
root cause

java.lang.NullPointerException
common.SessionCheck.sesCheck(SessionCheck.java:12)
org.apache.jsp.newjsp_jsp._jspService(newjsp_jsp.java:82)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.30 logs.

Apache Tomcat/7.0.30

Can anyone help me out this issue?

Claudiu Chelemen

Ranch Hand

Posts: 75

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posted 10 years ago

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Hello

The cause of the NullPointerException is clearly stated in the stacktrace:

Sumer Selvaraj wrote:
java.lang.NullPointerException
common.SessionCheck.sesCheck(SessionCheck.java:12)

Now, if you check line 12 in your SessionCheck class, what's the value of your session variable ?

Claudiu

bala nannaka

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Posts: 49

posted 10 years ago

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HttpSession session;

public boolean sesCheck() {
String sesValue = (String) session.getAttribute("status");

How does the session object passed to this class?

Sumer Selvaraj

Greenhorn

Posts: 15

posted 10 years ago

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Claudiu Chelemen wrote:Hello

The cause of the NullPointerException is clearly stated in the stacktrace:

Sumer Selvaraj wrote:
java.lang.NullPointerException
common.SessionCheck.sesCheck(SessionCheck.java:12)

Now, if you check line 12 in your SessionCheck class, what's the value of your session variable ?

Claudiu

I've passed the session variable in JSP page as following code

Further to check the the value I've removed the session.setAttribute() from the JSP page and added it to the class file

Now I'm getting error as the same.

Sumer Selvaraj

Greenhorn

Posts: 15

posted 10 years ago

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bala nannaka wrote:

HttpSession session;

public boolean sesCheck() {
String sesValue = (String) session.getAttribute("status");

How does the session object passed to this class?

I'm so sorry as I couldn't able to get your question. I'm a novice and developing an application for my final year degree project.

bala nannaka

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Posts: 49

posted 10 years ago

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import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

public class SessionCheck {

HttpServletRequest request;
HttpSession session;

public boolean sesCheck() {
session.setAttribute("status","test");
String sesValue = (String) session.getAttribute("status");
if (sesValue.equals("active"))
return true;
return false;
}
}

SessionCheck is a simple plain old java class .HttpSession will be not available for this class untill you pass it externally .

I would recomemnd you to pass it as a method parameter

and in jsp you pass it as a parameter

Sumer Selvaraj

Greenhorn

Posts: 15

posted 10 years ago

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bala nannaka wrote:

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

public class SessionCheck {

HttpServletRequest request;
HttpSession session;

public boolean sesCheck() {
session.setAttribute("status","test");
String sesValue = (String) session.getAttribute("status");
if (sesValue.equals("active"))
return true;
return false;
}
}

SessionCheck is a simple plain old java class .HttpSession will be not available for this class untill you pass it externally .

I would recomemnd you to pass it as a method parameter

import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; public class SessionCheck { HttpServletRequest request; HttpSession session; public boolean sesCheck(HttpSession session) { this.session = session session.setAttribute("status","test"); String sesValue = (String) session.getAttribute("status"); if (sesValue.equals("active")) return true; return false; } }

and in jsp you pass it as a parameter
<body> <% session.setAttribute("status", "Test"); SessionCheck sc = new SessionCheck(); boolean sesVal = sc.sesCheck(session); %> </body>

Thank you so much. It worked perfectly without any issues.

Don't get me started about those stupid light bulbs.