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Groups > comp.lang.java.programmer > #6760

Re: looping through a list, starting at 1

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On 8/1/2011 8:50 PM, Eric Sosman wrote:
> 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.

To add yet another option, if you are writing lots of iterations over 
the "tail" of a collection, then you could define an Iterable wrapping 
class, like this:

public class Tail<T> implements Iterable<T> {

   public static <T> Tail<T> tail(final Iterable<T> coll) {
     return new Tail<T>(coll);
   }

   public Iterator<T> iterator() {
     return iter;
   }

   private Iterator<T> iter;

   private Tail(final Iterable<T> coll) {
     iter = coll.iterator();
     if (iter.hasNext()) iter.next();
   }
}

then to use

   import static utils.Tail.tail;

   ...

   for (final E e : tail( list )) {
      ...
   }

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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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