Re: Class hierarchy uncertainty

From:
"Oliver Wong" <owong@castortech.com>
Newsgroups:
comp.lang.java.help
Date:
Wed, 20 Dec 2006 09:52:40 -0500
Message-ID:
<cmcih.124535$qD1.703679@wagner.videotron.net>
"Yuriy_Ivanov" <phantom_enigma@nospamhotmail.com> wrote in message
news:4eb7eb5b2124bbc7be0976247d313e3b@localhost.talkaboutprogramming.com...

Type 1 Type 2 Type 3 Type 4 Type5 Type classes
-Store attributes for pipe types
-(Constructors)
-(Access methods)
-(Update methods)
-Volume calculation method
-Cost calculation method


    My main concern with regards to your design is that it's not clear why
you have six different classes, instead of a single class. Compare these two
designs:

<design1>
abstract class Box {
  public abstract boolean isRed();
}

class RedBox extends Box {
  public boolean isRed() {
    return true;
  }
}

class NotRedBox extends Box {
  public boolean isRed() {
    return false;
  }
}
</design1>

<design2>
class Box {
  private boolean isRed;

  public boolean isRed() {
    return this.isRed;
  }
}
</design2>

    Your current design looks like design1, and I'm wondering why it
couldn't be made to look like design2 instead.

    - Oliver

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