Can someone explain in detail below given statements..
"we use the constructor, instead of init(), to initialize servlet. But you will not get the servlet specific things from constructor. The original reason for init() was that ancient versions of Java couldn�t dynamically invoke constructors with arguments, so there was no way to give the constructor a ServletConfig. That no longer applies, but servlet containers still will only call your no-arg constructor. So you won�t have access to a ServletConfig or ServletContext. "
This statement misses the point. Interfaces are used in Java to force an implementing object to have certain methods. "init(ServletConfig)" is part of the Servlet interface; that's where I can get the ServletConfig object if I need it. But the Java compiler can't force a class to have a constructor with a particular signature; so that would be an inferior approach that would introduce an additional error scenario for the container to handle.
As an aside, HttpServlet's "init()" method wasn't added until a later version of the Servlet API as a convenience method for those cases where a ServletConfig object wasn't required.
Servlets aren't the only place that work this way. Applets, too, are constructed by a container, and then their "init" method is called to let the applet code do any initialization that's required. [ August 13, 2008: Message edited by: Ulf Dittmer ]