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From "will mason (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LANG-1038) NumberUtils#isNumber() returns false for "+2" and true for "-2"
Date Wed, 24 Sep 2014 23:09:33 GMT

    [ https://issues.apache.org/jira/browse/LANG-1038?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14147054#comment-14147054
] 

will mason commented on LANG-1038:
----------------------------------

Documentation notwithstanding, there are two cogent pro points to keep in mind:

 1. In Java: int i = Integer.parseInt("+2"), produces: int = 2
 2. In mathematics: +2 is a number.

Also, for consistency, if isNumber("-1") is true, a leading plus sign will be expected to
be valid by end-users (not programmers).  A typical use case for isNumber() is to verify input
from a device, file or user input -- I submit that isNumber ought support syntax recognised
by parser functions such as, Integer.parseInt().

The point of discussion should be about user accessibility, serviceability & maintainability
of client code and accepted arithmetic notation. 

> NumberUtils#isNumber() returns false for "+2" and true for "-2"
> ---------------------------------------------------------------
>
>                 Key: LANG-1038
>                 URL: https://issues.apache.org/jira/browse/LANG-1038
>             Project: Commons Lang
>          Issue Type: Bug
>          Components: lang.math.*
>    Affects Versions: 3.1, 3.3.2
>            Reporter: will mason
>             Fix For: Discussion
>
>
> The strings {{"\+2"}} and {{"\+  2"}} give a "False" result when tested by {{isNumber()}}.
> Case one, {{"\+2"}} is legal with {{Integer.parseInt()}}.  Case two: {{"\+  2"}} gives
an exception with {{Integer.parseInt()}}.
> I believe the function should match legitimate inputs for the respective parser function
depending on the number type.
> Workaround: Use something like:
> {code:java}
> NumberUtils.isNumber( wrkStr.replaceFirst( "\\+", "") )
> {code}



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