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Re: Instantiate an abstract class

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In article <ini58c$8eh$2@news.albasani.net>, Lew <noone@lewscanon.com> 
wrote:

> Rob McDonald wrote:
> > Joshua Cranmer wrote:
> >> Rob McDonald wrote:
> >>> Now, we all know that you can't instantiate an abstract class -- 
> >>> but I want to anyway...  Actually, I would like my abstract class 
> >>> to be able to instantiate another instance of whatever concrete 
> >>> class it is at the time.
> 
> >> Your class is abstract, so you can easily have:
> >>
> >> abstract class AFoo {
> >>     public abstract AFoo makeInstance();
> 
> > That worked great.  I don't know why I hadn't come up with that 
> > solution myself.
> >
> > Most of my online searches had lead down the reflection path and I 
> > quickly got myself wrapped around the axle.  I'm going to go with 
> > the above implementation, but I am curious about how it could be 
> > made to work the other way.
> 
> Because you haven't yet read /Effective Java/ by Joshua Bloch.  You 
> must.  We all must, and not just once, either.
> 
> <http://java.sun.com/docs/books/effective/>
> The very first item of which is,
> "Item 1: Consider static factory methods instead of constructors"

Generously reprinted in Dr. Dobb's:

<http://drdobbs.com/java/208403883?pgno=1>

For convenient reference, now seen here:

<http://en.wikipedia.org/wiki/Factory_method_pattern>

-- 
John B. Matthews
trashgod at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>

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Instantiate an abstract class Rob McDonald <rob.a.mcdonald@gmail.com> - 2011-04-05 14:14 -0700
  Re: Instantiate an abstract class Patricia Shanahan <pats@acm.org> - 2011-04-05 14:37 -0700
    Re: Instantiate an abstract class Rob McDonald <rob.a.mcdonald@gmail.com> - 2011-04-05 14:49 -0700
  Re: Instantiate an abstract class Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-04-05 17:48 -0400
    Re: Instantiate an abstract class Rob McDonald <rob.a.mcdonald@gmail.com> - 2011-04-05 14:54 -0700
      Re: Instantiate an abstract class Patricia Shanahan <pats@acm.org> - 2011-04-05 15:09 -0700
      Re: Instantiate an abstract class Lew <noone@lewscanon.com> - 2011-04-06 12:43 -0400
        Re: Instantiate an abstract class "John B. Matthews" <nospam@nospam.invalid> - 2011-04-06 22:07 -0400
  Re: Instantiate an abstract class Roedy Green <see_website@mindprod.com.invalid> - 2011-04-05 19:02 -0700
  Re: Instantiate an abstract class Roedy Green <see_website@mindprod.com.invalid> - 2011-04-05 19:42 -0700
  Re: Instantiate an abstract class Lothar Kimmeringer <news200709@kimmeringer.de> - 2011-04-06 18:26 +0200
    Re: Instantiate an abstract class Lew <noone@lewscanon.com> - 2011-04-06 12:49 -0400
      Re: Instantiate an abstract class Patricia Shanahan <pats@acm.org> - 2011-04-06 10:09 -0700
      Re: Instantiate an abstract class Lothar Kimmeringer <news200709@kimmeringer.de> - 2011-04-07 01:01 +0200
  Re: Instantiate an abstract class Wojtek <nowhere@a.com> - 2011-04-06 12:41 -0700

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