init and destroy method

[felix thomas]

Can i call destroy method explicity from init method.

[Brahim Bakayoko]

I have never tried it, but I suspect an exception will be thrown since the servlet would not successfully initialize.

[Jeroen Wenting]

it's just a method so you can call it.
The only significance of the name destroy is that, given the correct signature, it will also be called during garbage collection.

[Kyle Brown]

It's actually not called during garbage collection, but during server shutdown -- but other than that, Jeroen's absolutely right -- it's just another method.

Kyle

[Brahim Bakayoko]

Actually, an execption will be thrown as I suspected:

 
 Did not realize  init() exception thrown by servlet InitializeDB: javax.servlet.ServletException

It is a method, but not any method.

[felix thomas]

This is the code and i don't get an exception.

import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class Inittesting extends HttpServlet
{
PrintWriter out=null;


public void init(ServletConfig s) throws ServletException
{

super.init(s);
System.out.println("in init before");
super.destroy();
System.out.println("in init");
}
public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException
{


try
{
//common instantiations required for the document login to build up
out=response.getWriter();

response.setContentType("text/html");

//super.destroy();
out.println("servlet now 33 ");

}catch(Exception e)
{
out.println("exception :"+e);

}
}



}

[Brahim Bakayoko]

This does on Websphere:

 
public class InitializeDB extends HttpServlet implements Servlet {
private ServletConfig servletConfig;
private ServletContext ctx;
private DataSource ds;

public void init(ServletConfig servletConfig) throws ServletException {
this.servletConfig = servletConfig;
this.ctx = servletConfig.getServletContext();

initDataSource();
destroy();// fails initialization
}

private void initDataSource(){
try {
InitialContext jndictx = new InitialContext();
DataSource ds = (DataSource) jndictx.lookup("java:comp/env/jdbc/psDS");
ctx.setAttribute(ContextInits.DS, ds);
this.ds = ds;
} catch (NamingException e) {
Logger logger = new Logger();
logger.logError(e);
}
}

..........

}

[Brahim Bakayoko]

Also, Thomas, can you show your initialization output?

[Jeroen Wenting]

yah, was confused with finalize()...
Too much reading about garbage collectors for my SCJP study lately

[Brahim Bakayoko]

Originally posted by Jeroen Wenting:
yah, was confused with finalize()...
Too much reading about garbage collectors for my SCJP study lately

Maybe a good time for a cold beer (an extra cold Guinness stout for me) and some good sleep.
Been there...