Re: [really patch] Re: HashMap putAll/putAllInternal bug

[Stuart Ballard]

Stephen Crawley wrote:
> The corollary is that if you can't provide a valid (and sufficiently
> efficient for your purposes) implementation for an abstract method in
> AbstractMap, then you should NOT be extending AbstractMap.  Rather you
> should be implementing the Map interface from scratch.

It doesn't matter whether I inherit from AbstractMap or not - I am, in 
fact, but it's irrelevant to the discussion at hand, because the code 
that's causing a problem is in HashMap, not AbstractMap, and it applies 
when a Map of my type is passed to putAll() on a HashMap.

The problem is that, while I could implement the size() method correctly 
on my Map type, it would be very slow, and hence all the algorithms 
which "optimize" by using size() instead of hasNext()* are 
pessimizations instead. And performance is important for my usage.

Stuart.

* Does anyone actually have a single example of a case where hasNext() 
is slow? Seems to me that it can never be significantly slower than 
size() because if it were, it could be implemented as "return counter < 
size()".

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Stuart Ballard, Senior Web Developer
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