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From: Robert Klemme <shortcutter@googlemail.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: Object orientation question
Date: Mon, 27 Oct 2014 23:51:30 +0100
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On 27.10.2014 21:51, Eric Sosman wrote:

 >      Clearly, the generated code is the same: AdditionInterface extends
 > BaseInterface, therefore any class implementing AdditionInterface also
 > necessarily implements BaseInterface.  If the class fails to provide a
 > method specified by BaseInterface, the code won't compile.  So the
 > question is purely about readability and style.

This is not fully correct: if you check with reflection you will see 
that there is a difference in what Class.getInterfaces() returns.

   public static void main(String[] args) {
     for (final Class<?> cl : Arrays.asList(Single.class, Both.class)) {
       System.out.println("Class name: " + cl.getName());

       for (final Class<?> ifac : cl.getInterfaces()) {
         System.out.println("  " + ifac.getName());
       }
     }
   }

yields in my test case

Class name: iface.inherit.Single
   iface.inherit.DerivedI
Class name: iface.inherit.Both
   iface.inherit.BaseI
   iface.inherit.DerivedI


>      Unless there's something rather unusual going on, I'd tend to favor
> brevity: Just say `class AdditionImpl implements AdditionInterface' and
> let it go at that.  Anyone who's curious about exactly what classes are
> extended and which interfaces are implemented can always consult the
> Javadoc, where it's all spelled out in gory detail.

I'm all with you on the readability through brevity here.  There is one 
more thing: by making AdditionInterface inherit BaseInterface the author 
clearly stated the intend that anything which implements 
AdditionInterface *is a* (or comprises) BaseInterface.  There is no need 
to express that again.  Since that inheritance is not likely to go away 
(such an interface change potentially affects a lot code and should thus 
not be done easily) there is no need to care for the case that the 
"extends" clause goes away leaving @Override dangling in AdditionImpl.

Kind regards

	robert