Groups > comp.lang.java.programmer > #6728

Re: looping through a list, starting at 1

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From	Eric Sosman <esosman@ieee-dot-org.invalid>
Newsgroups	comp.lang.java.programmer
Subject	Re: looping through a list, starting at 1
Date	Mon, 01 Aug 2011 21:50:59 -0400
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On 8/1/2011 6:45 PM, Stefan Ram wrote:
>    Assuming a list has a sufficient number of entries at run
>    time, what should be prefered to assign a reference to each
>    entry to »e«, starting at index 1:
>
> for( final E e : l.sublist( 1, l.size() ))...
>
>    or
>
> for( int i = 1; i<  l.size(); ++i ){ final E e = l.get( 0 ); ... }

     (ITYM l.get(i)?)

     How about

	Iterator<E> it = l.iterator();
	it.next();  // ignore element 0
	while (it.hasNext()) {
	    E e = it.next();
	    ...
	}

In short, there may well be half-a-dozen ways to do what you ask,
if not more.  None of them stands out as "preferred" to my eye;
you may as well do whatever seems natural.

     ... and "natural" is a little unnatural, it seems to me.  If
the various E are truly independent -- if l is merely a Collection
for the purposes of the loop -- one wonders where the interloper at
position 0 came from.  And if the position really matters -- maybe
you're looking at adjacent pairs or something -- then clearly i has
more significance than a purely synthetic iteration control would
(hence your second form would be preferred, because somewhere in the
body you'd be doing l.get(i-1).)  As a problem in the abstract I see
no clear reason to choose one form over its peers; with a concrete
context I might.

-- 
Eric Sosman
esosman@ieee-dot-org.invalid

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Re: looping through a list, starting at 1 Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-01 21:50 -0400
  Re: looping through a list, starting at 1 Patricia Shanahan <pats@acm.org> - 2011-08-01 20:34 -0700
    Re: looping through a list, starting at 1 Patricia Shanahan <pats@acm.org> - 2011-08-01 20:35 -0700
  Re: looping through a list, starting at 1 Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-02 07:31 -0400
  Re: looping through a list, starting at 1 Chris Riesbeck <Chris.Riesbeck@gmail.com> - 2011-08-02 14:38 -0500
    Re: looping through a list, starting at 1 markspace <-@.> - 2011-08-02 12:50 -0700
      Re: looping through a list, starting at 1 Chris Riesbeck <Chris.Riesbeck@gmail.com> - 2011-08-03 13:34 -0500

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