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https://issues.apache.org/jira/browse/COLLECTIONS-450?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13634483#comment-13634483
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Thomas Neidhart commented on COLLECTIONS-450:
---------------------------------------------
A collection provides an iterator over its elements, thus the notion of "first"
or "last" element is derived from the iteration order.
> Iterate over the all elements excluding the last/first one
> ----------------------------------------------------------
>
> Key: COLLECTIONS-450
> URL: https://issues.apache.org/jira/browse/COLLECTIONS-450
> Project: Commons Collections
> Issue Type: Wish
> Components: Collection
> Reporter: J. Moldawski
> Priority: Minor
> Attachments: patch_COLLECTIONS-450.txt
>
>
> The Problem
> ============
> In many applications you will extremly often find this sort of code:
> int i=0;
> for (element:elements)
> {
> i++;
> if (i!=elemets.size)
> {
> processLastElement(element);
> }else
> {
> // Just for last element
> processLastElement(element);
> }
> }
> It happens often, if not just all collections's elements themself must be
> processed, but some actions must be performed on going from one element to
> the next. Since the last element has no successor, this actions must be
> skipped when processing the last element. A very famous example is, if your
> are going the generate a comma-separated-vector from a Collection<String>:
> You will end up in a code like above.
> Proposal
> =========
> The method <T>CollectionUtils.forAllButLastDo(Collection<T>, C)
> should be introduced, which process all elements of a collection, but skips
> the last one, which will be just returned. The above code can be then
> re-written:
> processLastElement(forAllButLastDo(elements,
> new Closure<T>{
> execute(T element){
> processAllButTheLast(element)
> }
> }
> ))
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