servlet doubt

[trinadh reddy]

can i call a destroy()in doGet() explicitly?

I tried to call the init() from doGet() it works fine but when iam trying to call destroy() explicitly it is giving the nullpointer exception.

May i know the reason?

[Prabhu Venkatachalam]

For your First quetion:

init(),service(),destroy() are container callback methods and you should never call those.

But Of course yes, you can call those methods. Because servlet is also a class and it follows normal Java class rules.

For Second Question:

It looks strange to me. can you post your servlet class?

[trinadh reddy]

import java.io.IOException;
import javax.servlet.ServletException;
 
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
 
public class FirstServlet extends HttpServlet {
/**
* @see javax.servlet.http.HttpServlet#HttpServlet ()
*/
public FirstServlet() {
System.out.println("Welcome tyo servlet programming");

}
 
/**
* @see javax.servlet.GenericServlet#void ()
*/
public void destroy() {
 
//super.destroy();
 
}
 
/**
* @see javax.servlet.http.HttpServlet#void (javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
*/
public void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
System.out.println("doget");
FirstServlet fs= new FirstServlet();
System.out.println(fs);
                  fs.destroy();
                 }
 
/**
* @see javax.servlet.http.HttpServlet#void (javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
*/
public void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {

System.out.println("dopost");
FirstServlet fs1= new FirstServlet();
 
}
 
/**
* @see javax.servlet.GenericServlet#void ()
*/
public void init() throws ServletException {
System.out.println("init");

 

 
}
}

[BPSouther: Added UBB Code Tags]
[ November 16, 2006: Message edited by: Ben Souther ]

[Ben Souther]

trinadh reddy,

You would do well to read through the Servlet Spec; especially the sections on the "Servlet Lifecycle". (link in my signature)

You don't instanciate servlets with the new keyword.
The container does this for you.

Also, as Prabhu venkatachalam has mentioned, the methods listed above are call back methods. In other words, they are placeholders for your code. The container calls these methods at the appropriate time, You don't call them yourself.
You can override the init and destroy methods and add any code that you want to have run at startup and shutdown.
Do not override the service method directly.
Instead override doGet or doPost.