Re: a question for sorting keys in Map

From:

Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 20 Nov 2007 11:05:21 -0800

Message-ID:

<nL6dnfnDwPJhst7anZ2dnUVZ_uyinZ2d@wavecable.com>

www wrote:

Hi,

I have a Map, actually a TreeMap, which will automatically sort the keys
alphabetically. The keys are Strings, like "VARIABLE" + i, e.g:
VARIABLE0, VARIABLE1, VARIABLE2, etc.

If the total number of entries < 10, then the sorted order is ok:

VARIABLE0
VARIABLE1
VARIABLE2

But, if the total number of entries > 10, the sorted order is not what I
want:

VARIABLE0
VARIABLE1
VARIABLE10
VARIABLE11
VARIABLE12
...
VARIABLE2
VARIABLE20
VARIABLE21
...
VARIABLE3
VARIABLE30
VARIABLE31
...

I want the order be:
VARIABLE0
VARIABLE1
VARIABLE2
...
VARIABLE9
VARIABLE10
VARIABLE11
....

Can you help me to achieve this? Thank you very much.

I suggest not using a map of Strings in this case:

SortedMap<Integer, Something>;

Or, using a List
List<Something>

If you absolutely must using Strings, then tell me this:
Which order would these strings be in? A1B10, B2A9

Regardless of your answer there, you'll need to write a
Comparator<String> implementation that will give the correct ordering.

Hope this helps,
Daniel.

--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>