RE: Servlet question, WAS 3.5.2

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

The syntax "super.init()" calls the init() method of my parent.  This is a 
general procedure when overriding a parent method.  When overriding a method 
(rather than adding your own new method), it's a good idea to invoke your 
parent's method as well, in case it's doing some stuff that you need.  It's an 
especially good idea with constructors:

MyNewClass()
{
  super();   // Call my superclass's constructor
  myInit();  // Do my initialization
}

There are times when you DON'T want to call the parent's method, but you better 
be very familiar with what the parent is doing when you make that decision.

Here's an example I use when I teach: I have a TV class.  The init method turns 
on the TV.  Then I create a VCR/TV combo that subclasses the television.  The 
init method turns on the VCR.  When I call the init method for the new TV/VCR 
object, the VCR runs but I get a black screen - why?  Because I didn't call the 
TV's init routine, which turns on the TV.

Hope this helps.

Joe

---------- Original Message ----------------------------------
From: "Stone, Brad V (TC)" <bvstone@taylorcorp.com>
Reply-To: JAVA400-L@midrange.com
Date: Thu, 8 Feb 2001 07:16:12 -0600 

>Ok, one more question while we're on the subject.  Some of the examples I
see have this:
  public void init(ServletConfig config) throws ServletException
  {
    super.init(config);
  }

Some don't.  I know what the init method is for, but why is it in some
examples and not in others?  And what does super.init(config) do?  


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