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Posted to issues@commons.apache.org by "Sebb (JIRA)" <ji...@apache.org> on 2012/09/29 01:47:08 UTC
[jira] [Commented] (LANG-839) ArrayUtils removeElements methods use
unnecessary HashSet
[ https://issues.apache.org/jira/browse/LANG-839?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13466020#comment-13466020 ]
Sebb commented on LANG-839:
---------------------------
Note that the current implementation creates a HashMap of size values.length to hold the numbers of each value found, so a large values array will cause problems anyway.
> ArrayUtils removeElements methods use unnecessary HashSet
> ---------------------------------------------------------
>
> Key: LANG-839
> URL: https://issues.apache.org/jira/browse/LANG-839
> Project: Commons Lang
> Issue Type: Improvement
> Components: lang.*
> Affects Versions: 3.1
> Reporter: Sebb
> Priority: Minor
>
> The removeElements() methods use a HashSet to collect the indexes that need removing.
> This requires creating Integer objects for each index, and the HashSet then has to be converted into an int[] array.
> It would be more efficient to store the entries in an actual int[] array.
> The maximum size of this is the length of the values array (or the length of the input array if that is shorter).
> The array must be truncated before calling the private removeAll() method; this can be done with Arrays.copyOf(x[], length).
> However, if the arrays are very large, and most of the values do not appear in the input, this might result in using more memory than the HashSet implementation.
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