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From Benedikt Ritter <brit...@apache.org>
Subject Re: [lang] Allocate array of the correct size
Date Tue, 05 May 2015 12:52:49 GMT
Hello Jörg,

2015-05-05 8:30 GMT+02:00 Jörg Schaible <joerg.schaible@swisspost.com>:

> Hi Benedikt,
>
> britter@apache.org wrote:
>
> > Repository: commons-lang
> > Updated Branches:
> >   refs/heads/master 8548b12d8 -> 60b32953a
> >
> >
> > Allocate array of the correct size
> >
> >
> > Project: http://git-wip-us.apache.org/repos/asf/commons-lang/repo
> > Commit:
> > http://git-wip-us.apache.org/repos/asf/commons-lang/commit/60b32953
> Tree:
> > http://git-wip-us.apache.org/repos/asf/commons-lang/tree/60b32953 Diff:
> > http://git-wip-us.apache.org/repos/asf/commons-lang/diff/60b32953
> >
> > Branch: refs/heads/master
> > Commit: 60b32953a968e5623f82a6b27d6c679bc17c48e5
> > Parents: 8548b12
> > Author: Benedikt Ritter <britter@apache.org>
> > Authored: Mon May 4 21:26:07 2015 +0200
> > Committer: Benedikt Ritter
> > <britter@apache.org> Committed: Mon May 4
> > 21:26:07 2015 +0200
> >
> > ----------------------------------------------------------------------
> >  .../apache/commons/lang3/builder/ReflectionToStringBuilder.java    | 2
> +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > ----------------------------------------------------------------------
> >
> >
> >
> http://git-wip-us.apache.org/repos/asf/commons-lang/blob/60b32953/src/main/java/org/apache/commons/lang3/builder/ReflectionToStringBuilder.java
> > ----------------------------------------------------------------------
> > diff --git
> >
>
> a/src/main/java/org/apache/commons/lang3/builder/ReflectionToStringBuilder.java
> >
>
> b/src/main/java/org/apache/commons/lang3/builder/ReflectionToStringBuilder.java
> > index 5904469..7a78170 100644 ---
> >
>
> a/src/main/java/org/apache/commons/lang3/builder/ReflectionToStringBuilder.java
> > +++
> >
>
> b/src/main/java/org/apache/commons/lang3/builder/ReflectionToStringBuilder.java
> > @@ -333,7 +333,7 @@ public class ReflectionToStringBuilder extends
> > ToStringBuilder {
> >                  list.add(e.toString());
> >              }
> >          }
> > -        return list.toArray(ArrayUtils.EMPTY_STRING_ARRAY);
> > +        return list.toArray(new String[list.size()]);
> >      }
>
> What's the benefit of this? Where's the difference by letting
> List.toArray()
> allocate the appropriate array compared to do it on your own?
> ArrayUtils.EMPTY_STRING is a constant after all, so there's no additional
> allocation.
>

I changed this because my IDE complained about that line of code:

"Call to 'toArray' with zero-length array argument
'ArrayUtils.EMPTY_STRING_ARRAY'

Reports any call to 'toArray' on an object or type or subtype of
java.util.Collection with a zero-length argument. When passing an array of
too small size, the toArray() method has to construct a new array of the
correct size using reflection. This has significantly worse performance
than passing in an array of at least the size of the collection itself."

To be honest, I did not do any performance benchmarks to make sure this is
really true.

Benedikt


>
> - Jörg
>
>
>
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-- 
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http://www.systemoutprintln.de/
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