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using item in arraylist as order

Lucas Franceschi
Ranch Hand

Joined: Nov 10, 2008
Posts: 106

ok, this is my problem.
i got a hashmap(dados), as the values of this hasmap, I got arraylists.

I'm having a great fight with java here.

thats b'cuz I need to sort the hashmap, according to one item of the arraylist.

what i'm trying to do right now is:

but I really (Really.) think that I make it easier.

the argument dados(HashMap) is my "master" Hashmap. and sorry if the comments and variable names are in portuguese, i'm brazilian.


Lucas Franceschi
Software Developer for SGI Sistemas, lukas1596@gmail.com
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 32689
    
    4
You can't sort a HashMap. There are other Map implementations which can be sorted, see this interface.
Lucas Franceschi
Ranch Hand

Joined: Nov 10, 2008
Posts: 106

it needs to be a hashmap.
Ernest Friedman-Hill
author and iconoclast
Marshal

Joined: Jul 08, 2003
Posts: 24057
    
  13

Originally posted by Lucas Franceschi:
it needs to be a hashmap.


Well, something somewhere has to give, because by definition, the keys (and values) in a HashMap are not sorted in any user-controlled way, and there's nothing you can do about that.

Can you make a new collection containing the sorted keys (or values, I'm confused?)

Can you use TreeMap, which lets you store your data sorted?


[Jess in Action][AskingGoodQuestions]
Lucas Franceschi
Ranch Hand

Joined: Nov 10, 2008
Posts: 106

ok, I understand.

But the case is that I dont need to have an sorted HashMap, I only need to be able to read it in order(ordering it by the [5] position on the arraylists.)

anyuone got any soggestions on how to do that?
Joanne Neal
Rancher

Joined: Aug 05, 2005
Posts: 3011
    
    9
Originally posted by Lucas Franceschi:
ok, I understand.

But the case is that I dont need to have an sorted HashMap, I only need to be able to read it in order(ordering it by the [5] position on the arraylists.)

anyuone got any soggestions on how to do that?


You can't directly iterate over the entries in a Hashmap. You need to extract either the values, keys or key/value pairs into a Collection of some sort, which I think is what you have already done.


Joanne
Lucas Franceschi
Ranch Hand

Joined: Nov 10, 2008
Posts: 106

ok joanne, I appreciate the help, I just wanted to know if there was something else to be done.
thanks you all guys, helped me a lot.


i'm closing the topic...
Lucas Franceschi
Ranch Hand

Joined: Nov 10, 2008
Posts: 106

well I think i'm newbie, and I can't close the topic, so please, this topic is no more useful, please do not waste your time with this...
I appeciate the help I got, but that will not be necessary anymore.
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 32689
    
    4
We don't close threads unless there is something wrong with them. They simply disappear into the shadows until somebody comes along years later and posts a reply!
Lucas Franceschi
Ranch Hand

Joined: Nov 10, 2008
Posts: 106

ok, i'm jsut starting at javaranch.
Martijn Verburg
author
Bartender

Joined: Jun 24, 2003
Posts: 3268

No worries Lucas, we like to keep threads around so that people who perform searches can find solutions to similar problems, happy coding!


Cheers, Martijn - Blog,
Twitter, PCGen, Ikasan, My The Well-Grounded Java Developer book!,
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