Keying a collection by type
<p>I'm looking to have a collection of objects that implement a certain interface, but I'd like to only have one per concrete type within the collection.</p>

<pre><code>collection of implementers of dog:
 - instance of dachshund
 - instance of beagle
 - instance of corgi
</code></pre>

<p>In .NET, there's a "KeyedByTypeCollection".  Does something similar exist in Java in such a way that I could use it on Android?</p>

<p>Thanks!</p>
