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Date: Mon, 19 May 2008 22:00:55 -0700 (PDT)
From: "Julius Davies (JIRA)" <jira@apache.org>
To: issues@commons.apache.org
Subject: [jira] Commented: (COLLECTIONS-296) Introduce SortedUtils.merge()
 for merging sorted collections
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    [ https://issues.apache.org/jira/browse/COLLECTIONS-296?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12598173#action_12598173 ] 

Julius Davies commented on COLLECTIONS-296:
-------------------------------------------

Thanks very much for the feedback!  I worry that consumer won't properly initialize Collection "res" to the right capacity (a.size() + b.size()).  Also, if the consumer wants to put the elements in a different collection, they can always use Collection.addAll() with the ArrayList that's returned.

Here are some more methods I'm thinking of adding:

<code>
boolean isSorted(Collection coll);
boolean isSorted(Collection coll, Comparator c);

int binarySearch(List l, Object o);
int binarySearch(List l, Object o, Comparator c);
</code>

There's another reason I like returning ArrayList:  it can be easily fed into the binarySearch() method I'm thinking of adding.  LinkedList *can* be fed into binarySearch, but it's a bad idea!


> Introduce SortedUtils.merge() for merging sorted collections
> ------------------------------------------------------------
>
>                 Key: COLLECTIONS-296
>                 URL: https://issues.apache.org/jira/browse/COLLECTIONS-296
>             Project: Commons Collections
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Julius Davies
>            Priority: Minor
>         Attachments: SortedUtils.patch
>
>
> Is there any interest in this?
>     /**
>      * Returns a new ArrayList where sorted Collection a and sorted Collection b
>      * are combined such that ordering of the elements according to
>      * Comparator c is retained.  Uses the standard O(n) merge algorithm
>      * for combining two sorted lists.
>      *
>      * @param a Object to combine with sorted Collection b.  Must implement Comparable.
>      * @param b Sorted Collection to combine with Object a.
>      * @param c Comparator by which Collection a and Collection b have been sorted, or null
>      *          if the Collections are sorted according to their natural ordering.
>      * @return a new sorted ArrayList
>      */
>     public static ArrayList merge(Collection a, Collection b, Comparator c);

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