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From Rob Oxspring <>
Subject Re: [collections] TransformedCollection
Date Sun, 08 May 2005 19:06:47 GMT
Thanks James,

The latter scenario is exactly the one I keep finding myself in!  I 
guess it's the naming that throws me - the collect() methods provide 
what I'd expect of transformedCollection() under a name that seems 
pretty abstract, whereas the implementation of transformedCollection() 
seem more suited to a method called transformingCollection(), although 
this could turn into a bike shed issue very quickly.

Seriously though, would it be reasonable to deprecate the collect() 
methods in favour of something with 'transform' in the name? I'm not 
sure what name to suggest but the word 'collect' might as well be 
dropped as all CollectionUtils methods are implicitly about collecting :)

In the meantime, thanks for the pointer to the collect() family of 
methods, I may well add some cross references in the javadocs between 
these and the transformedCollection() method to try and avoid future 


James Carman wrote:
> Are you wanting to add dates to the resulting collection and have them
> transformed into Strings?  Or, are you just looking for a collection of
> Strings that you don't need to modify which represent the dates?  If it's
> the latter, you should use the CollectionUtils.collect() method rather than
> the transformedCollection() method.  I too have been burned by that very
> thing.  Just by looking at the name, it would seem that
> transformedCollection() would return a collection which was the result of
> applying the transformer to the input collection.  Not so!  I've learned
> that the hard way a few times (bad memory).
> -----Original Message-----
> From: Rob Oxspring [] 
> Sent: Saturday, May 07, 2005 11:42 AM
> To: Jakarta Commons Developers List
> Subject: [collections] TransformedCollection
> Hi,
> I've just been burnt (and not for the first time) by the fact that the 
> TransformedCollection doesn't transform the objects that are already in 
> the wrapped collection.  For example:
> Collection dates = ... // a collection with Date objects in it Transformer
> toString = ... // a transformer that calls toString Collection strings =
>      CollectionUtils.transformedCollection(dates,toString);
> My intuition tells me that strings should be full of String objects and 
> have no Date objects in it but the opposite is true.  Is this the 
> intended behaviour or is this a bug?  I'm happy to patch the 
> TransformedCollection class but wanted to run it passed people first...
> Thanks,
> Rob
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