[Collections] ListUtils.transformedList unaffected by invokerTransformer ?

[Laurent Perez <ha...@gmail.com>]

Hi !

Not sure if this is a bug or intended behaviour, given the following code :

Transformer t = TransformerUtils.invokerTransformer("toLowerCase");
List<String> abc = new ArrayList<String>();
abc.add("A");
List<String> tabc = ListUtils.transformedList(abc, t);
System.out.println("tabc:" + tabc);

This will return : tabc:[A] instead of tabc:[a].

A single transform works, String a = (String)t.transform("A"); will
return a lowercase "a".

Is it a bug ?

Thanks
laurent



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RE: [Collections] ListUtils.transformedList unaffected by invokerTransformer ?

[Jörg Schaible <Jo...@Elsag-Solutions.com>]

Hi Laurent,

Laurent Perez wrote on Friday, August 31, 2007 1:08 PM:

> Hi !
> 
> Not sure if this is a bug or intended behaviour, given the following
> code : 
> 
> Transformer t = TransformerUtils.invokerTransformer("toLowerCase");
> List<String> abc = new ArrayList<String>();
> abc.add("A");
> List<String> tabc = ListUtils.transformedList(abc, t);
> System.out.println("tabc:" + tabc);
> 
> This will return : tabc:[A] instead of tabc:[a].
> 
> A single transform works, String a = (String)t.transform("A"); will
> return a lowercase "a". 
> 
> Is it a bug ?

It's defined behaviour. A transformer will only transformed new elements, not the ones already available in the collection. This is, because the TransformedList is a decorator for the original. See http://commons.apache.org/collections/api-release/org/apache/commons/collections/list/TransformedList.html#TransformedList(java.util.List,%20org.apache.commons.collections.Transformer)

- Jörg

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