[jira] Commented: (LANG-269) Shouldn't Commons Lang's StringUtils have a "common" string method?

["Michael Dang (JIRA)" <ji...@apache.org>]

    [ http://issues.apache.org/jira/browse/LANG-269?page=comments#action_12419905 ] 

Michael Dang commented on LANG-269:
-----------------------------------

Scott, I think this is a very elegant approach.  I like the method name getCommonPrefix and the idea of adding the indexOfDifference(String[]) method.  However, I would like to add one comment about the indexOfDifference(String[]) calling indexOfDifference(String, String).  Looking from the performance angle, this may not be an efficient implementation.  

For example, if most of the strings are long and pretty much the same except the last string is very short (or null), all the beginning comparisions are wasted.  Although it is very natural to call indexOfDifference(String, String) from within indexOfDifference(String[]), I would think that it would perform better if we just scan through strings vertically, char by char, and short circuit out once the first difference char is found.

Feel free to disagree and I maybe worrying about performance too much.  :)

--Michael

> Shouldn't Commons Lang's StringUtils have a "common" string method?
> -------------------------------------------------------------------
>
>          Key: LANG-269
>          URL: http://issues.apache.org/jira/browse/LANG-269
>      Project: Commons Lang
>         Type: New Feature

>  Environment: generic
>     Reporter: Michael Dang
>      Fix For: 3.0
>  Attachments: StringUtils.patch
>
> A method which accepts a string array and returns a string which is the common portion of all the strings starting from the left, or more general form of that.
> This is very common operation.  For example, one may want to find the common directory of a set of path strings.
> passing in:
> "/foo/f1.txt"
> "/foo/moo/f2.txt"
> "/foo/moo/f3.txt"
> should returns "/foo/"
> It is tedious to implement this in every project.  And I think Commons Lang StringUtils should have some methods to help in this.

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