Question

I like to know why dont we call servlet constructor instead of init method to initialize the config parameters.

THanks

Answer 1

This thread should clarify the differences.

Quoting from one of the more illuminating posts:

The init() method is typically used to
perform servlet
initialization–creating or loading
objects that are used by the servlet
in the handling of its requests. Why
not use a constructor instead? Well,
in JDK 1.0 (for which servlets were
originally written), constructors for
dynamically loaded Java classes (such
as servlets) couldn’t accept
arguments. So, in order to provide a
new servlet any information about
itself and its environment, a server
had to call a servlet’s init() method
and pass along an object that
implements the ServletConfig
interface. Also, Java doesn’t allow
interfaces to declare constructors.
This means that the
javax.servlet.Servlet interface cannot
declare a constructor that accepts a
ServletConfig parameter. It has to
declare another method, like init().
It’s still possible, of course, for
you to define constructors for your
servlets, but in the constructor you
don’t have access to the ServletConfig
object or the ability to throw a
ServletException.