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From: Robert Klemme <shortcutter@googlemail.com>
Newsgroups: comp.lang.java.programmer
Subject: Re: Glitch in Java Collections (No descendingMap in LinkedHashMap)
Date: Thu, 04 Oct 2012 23:01:48 +0200
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On 04.10.2012 14:09, Jan Burse wrote:
> Dear All,
>
> I just wonder whether I have overlooked something.
> But could it be that LinkedHashMap is lacking the
> following API:
>
>     Map<K,V> descendingMap();
>
> So I can only iterate from oldest to youngest, and
> not the other direction?

I guess they omitted it because the purpose is to provide a Map which 
always returns elements in insertion order (and not reverse insertion 
order).

> Although under the hood it uses a double linked list,
> and a reverse iterator would be simple.
>
> Also the whole matter seems to be complicated, since
> the other collections have descendingMap() in an
> Interface NavigableMap, which extends SortedMap.

There you see why it's not in LinkedHashMap: it's neither a NavigableMap 
nor a SortedMap.

> But SortedMap map assumes a compartor, whereby the
> sorting in LinkedHashMap is implicit.

There is no sorting going on - you just get insertion order.

Cheers

	robert

-- 
remember.guy do |as, often| as.you_can - without end
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