Re: foreach and stack, iterating from the bottom-up?

From:
Piotr Kobzda <pikob@gazeta.pl>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 06 May 2008 09:36:22 +0200
Message-ID:
<fvp1pm$c72$1@inews.gazeta.pl>
WP wrote:
....

It's not an actual
problem, I simply adapted my logic in the method to this behavior,
but, as I said, I was surprised.


It's possible to achieve what you want, without adapting it in your logic:

import java.util.*;

public class ReverseStackIteration {

   public static void main(String[] args) {
     Stack<String> stack = new Stack<String>();
     stack.addAll(Arrays.asList("1", "2", "3", "4"));

     System.out.println("default iteration:");
     for(String e : stack)
       System.out.println(e);

     System.out.println("reverse iteration:");
     for(String e : reverseIterable(stack))
       System.out.println(e);
   }

   public static <E> Iterable<E> reverseIterable(
       final List<E> list) {
     return new Iterable<E>() {

       @Override
       public Iterator<E> iterator() {
         final ListIterator<E> iter
             = list.listIterator(list.size());
         return new Iterator<E>() {

           @Override
           public boolean hasNext() {
             return iter.hasPrevious();
           }

           @Override
           public E next() {
             return iter.previous();
           }

           @Override
           public void remove() {
             iter.remove();
           }
         };
       }
     };
   }

}

piotr

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