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From "Scott Johnson (JIRA)" <>
Subject [jira] Commented: (LANG-269) Shouldn't Commons Lang's StringUtils have a "common" string method?
Date Sun, 09 Jul 2006 20:22:30 GMT
    [ ] 

Scott Johnson commented on LANG-269:

Thank you, Michael.

The indexOfDifference(String[]) method initially scans the String array for the shortest String
and uses that in the comparisons.  So I don't think there is a performance issue with the
scenario where there are a bunch of long strings with a final short string.  In fact, the
algorithm should be pretty efficient because it'll compare only few characters of the long

But your idea of comparing the first character in each string then the second, third, etc,
is more efficient in some scenarios.  For example, if there are a large number of long, similar
strings with a few very different strings mixed in.  This algorithm will reduce the number
of comparisons in that case.

When I get some time this afternoon, I'll give that a try.

Thanks for the suggestion.


> Shouldn't Commons Lang's StringUtils have a "common" string method?
> -------------------------------------------------------------------
>          Key: LANG-269
>          URL:
>      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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