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Re: state design pattern: question: inner or outer class: which is better?

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From	Lew <lewbloch@gmail.com>
Newsgroups	comp.lang.java.programmer
Subject	Re: state design pattern: question: inner or outer class: which is better?
Date	Fri, 2 Dec 2011 07:27:49 -0800 (PST)
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 Roedy Green wrote:
> John Goche wrote, quoted or indirectly quoted someone who said :
>> I am implementing the state design pattern to manage a set of
>> sprites in a game. I wonder if anyone could tell me whether it
>> is better to implement the state classes as inner classes of the
>> object they are a state of, or as outer classes each being passed
>> a reference to the sprite object they are being a state for.
> 
> There are two main reasons to use inner classes:
> 
> 1.  When the inner classes need to intimately access the fields of a
> particular mother object they are attached to.
> 
> 2. When you want scope to partly shield the inner classes from the
> outside. They treated somewhat as if they were part of the mother
> class.

This second point applies to static nested classes as well.  Obviously if the needed "fields of a ... mother object" are not static, then only an inner class will do for point #1.  If they are static, then the nested class can be as well.

-- 
Lew

Thread

state design pattern: question: inner or outer class: which is better? John Goche <johngoche99@googlemail.com> - 2011-11-30 09:22 -0800
  Re: state design pattern: question: inner or outer class: which is better? Lew <lewbloch@gmail.com> - 2011-11-30 11:22 -0800
    Re: state design pattern: question: inner or outer class: which is better? Gene Wirchenko <genew@ocis.net> - 2011-11-30 14:04 -0800
      Re: state design pattern: question: inner or outer class: which is better? Lew <lewbloch@gmail.com> - 2011-11-30 14:28 -0800
        Re: state design pattern: question: inner or outer class: which is better? Gene Wirchenko <genew@ocis.net> - 2011-11-30 15:03 -0800
          Re: state design pattern: question: inner or outer class: which is better? Lew <lewbloch@gmail.com> - 2011-11-30 19:10 -0800
            Re: state design pattern: question: inner or outer class: which is better? Gene Wirchenko <genew@ocis.net> - 2011-11-30 19:23 -0800
  Re: state design pattern: question: inner or outer class: which is better? Roedy Green <see_website@mindprod.com.invalid> - 2011-12-02 01:47 -0800
    Re: state design pattern: question: inner or outer class: which is better? Lew <lewbloch@gmail.com> - 2011-12-02 07:27 -0800
  Re: state design pattern: question: inner or outer class: which is better? Arne Vajhøj <arne@vajhoej.dk> - 2011-12-02 21:32 -0500

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