getServletContext() returning null

[Sameer Damle]

i am trying to excecute the following code it gets compiled but when i call that servlet i am getting null pointer exception.

the code is as follows.....

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
 

public class Versionservlet extends HttpServlet
{
ServletContext ctx = null;
 
public void init(ServletConfig cfg) throws ServletException
{
System.out.println("-----------------------------");
System.out.println("    Versionservlet started   ");
System.out.println("-----------------------------");
}
public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException,IOException
{
res.setContentType("text/html");
PrintWriter pw = res.getWriter();
 
pw.println("The version Servlet Started...........");
 
ctx = getServletContext();
 
pw.println(ctx.getMajorVersion());
pw.println(ctx.getMinorVersion());
}
}
 

thanks in advanced.

[David O'Meara]

How are you calling the Servlet? ie have you provided a servlet mapping?

[Sameer Damle]

yes i have provided mapping for the servlet

    
 <servlet>
    <servlet-name>Versionservlet</servlet-name>
    <servlet-class>Versionservlet</servlet-class>
  </servlet>
 
....
 
<servlet-mapping>
    <servlet-name>Versionservlet</servlet-name>
    <url-pattern>/Versionservlet</url-pattern>
  </servlet-mapping>

i am calling the sevlet using the url

http://172.20.44.85:7001/sameer/Versionservlet

[Christophe Verré]

You have overridden init(ServletConfig) so you should store the servletConfig somewhere, or call the parent's init method.

In your init():
Either ctx = cfg.getServletContext();
Or super.init(cfg);


Overriding the init() method will prevent the default mechanism, so HttpServlet won't store the ServletConfig for you. That's why getServletContext() will cause NullPointerException.
[ January 26, 2006: Message edited by: Satou kurinosuke ]

[Sameer Damle]

thanks satou...

i just called super.init() from the overridden init()....

that solved the purppose...

thanks once again for prompt help....

[David O'Meara]

D'oh, nice catch.

[Vishnu Prakash]

Hi Sameer Damle

Just update the servlet FAQ. Take a look at it to have a better understanding of init() and init(ServletConfig config).

I request moderators to erase the question marks and make it look better.

[Jacques Traore]

Christophe Verré wrote:You have overridden init(ServletConfig) so you should store the servletConfig somewhere, or call the parent's init method.

In your init():
Either ctx = cfg.getServletContext();
Or super.init(cfg);


Overriding the init() method will prevent the default mechanism, so HttpServlet won't store the ServletConfig for you. That's why getServletContext() will cause NullPointerException.
[ January 26, 2006: Message edited by: Satou kurinosuke ]

Thank you very much Mr Verré.
Four years later, you always helps someone else.