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Re : Convert List to Map

by gonzalad :: Rate this Message:

Thanks

Your sample works fine for my use case (that's exactly what I'm doing in my code), but I was wondering about such utility thing just after looking at :
http://commons.apache.org/collections/api-release/org/apache/commons/collections/map/TransformedMap.html#decorate(java.util.Map,%20org.apache.commons.collections.Transformer,%20org.apache.commons.collections.Transformer)
which is a map-to-map conversions.

Since commons-collection provides map-to-map conversion, why does'nt it provide list-to-map conversion with the same logic ?

________________________________
De : Ted Dunning <ted.dunning@...>
À : Commons Users List <user@...>
Envoyé le : Jeudi, 11 Juin 2009, 23h12mn 10s
Objet : Re: Convert List to Map

How is this easier than this:

Map m = new HashMap();
for (SpecificObject x : list) {
m.put(s.getId(), s.getDescription());
}

?

Why make this soo much harder than it needs to be?

On Wed, Jun 10, 2009 at 12:19 PM, Adrian Gonzalez <adr_gonzalez@...>wrote:

> Hello,
>
> I have the same question as
> http://mail-archives.apache.org/mod_mbox/commons-user/200509.mbox/%3C878e7290050905002752ed543d@...%3E:
>
> I need to do a lot of list-to-map conversions, and I'm looking for a way to
> use commons collections for this.
> I would like to do something like this:
>
> Map map = ListUtils.toMap(list, new SomeTransformerInterface() {
> void insertIntoMap(Object object, Map map) {
> SpecificObject s = (SpecificObject) object;
> map.put(s.getId(), s.getDescription());
> }
> });
>
> Is there a way to do that with commons collection ?
>
> Thank you very much
>
>
>

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Ted Dunning, CTO
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