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From: Jim Janney <jjanney@shell.xmission.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: how to trim() a String only at the right side?
Date: Thu, 26 Sep 2013 09:44:38 -0600
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markspace <markspace@nospam.nospam> writes:

> On 9/25/2013 6:55 AM, Andreas Leitgeb wrote:
>> I'd need to trim only *trailing* whitespace off a String (or StringBuilder)
>> while preserving leading white space. Furthermore (unlike trim()), I'd only
>> strip exact \u0020 chars, no other control chars.
>>
>> I could code a while-loop to search for last non-\u0020 char position and then
>> extract the approriate substring (or delete() the spaces), but if there is a
>> more elegant solution that I've missed in the javadocs, then I'd be glad about
>> a hint.
>>
>> PS: no need to code out any solutions involving explicit loops.
>> PPS: target is Java SE 7
>>
>
>
> Other than download some Apache string utils, I don't think there is
> anything better than just using a loop.  Most of the examples here
> were fairly in efficient: extra concatenation or recursion are going
> to be less efficient, potentially *a lot* less efficient.

In older versions of Java where substring takes constant time, the time
for the recursive version would be proportional to the number of
trailing blanks: the main concern would probably be stack overflow.  In
more recent implementations, where substring does an actual copy, it
could potentially take quadratic time--definitely not a good idea.  I
agree that if speed is wanted a loop is the best approach.  The
existence of the Apache util suggests that there isn't a good solution
in the JRE library.

-- 
Jim Janney