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Thread: Should i use a hashmap?

  1. #1
    Junior Member
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    Default Should i use a hashmap?

    Hey guys. I heard good things of this forums so i came to give it a try. Please be patient on me as i am new to java programming or programming in general for that matter.

    So, i'm going to be honest with you. I have an assignment due next week where i need to create a project in java where i would have a class called events, one named artists and another named Simulator where everything takes place. So one artist may be associated with one or more events and one event must have at least one artist. I already tried it with arraylists and got it to work but it is a mess and i did a bit of cheating. Sssshhh don't tell anyone So i thought about associative arrays aka hashtables and/or hashmaps. I know the syntax of these guys, what i lack is the how to implement this. So I thought I should have something like

    HashMap<events, artists> listOfEvents = new HashMap<events, artists>();
    ArrayList<artists> listOfArtists = new ArrayList<artists>();

    Does this make sense? I know a hashmap consists of a pair (key,value)... I'm lost here guys. Help me.

  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: Should i use a hashmap?

    HashMaps maps one key to one item. You can map the same item to multiple keys. However, in a HashMap all keys must be unique so you can't map multiple items to the same key. I don't see HashMaps helping you anymore than ArrayLists (on the contrary, they would be more cumbersome).

    If you're allowed to change the the artist (or event) class, that would be the way to go. Simply add to the artist (or event) class any collection you like of events. By virtue, any event could turn up in different artist's collections of events, and an artist can contain multiple events.

    Otherwise, you could look into using graphs. Simply define a graph which can contain both events and artists as nodes, then define edges which would link artists to their associated events and vise-versa. Technically such a graph layout could allow you to associate an artist with another artist, or an event with another event, but if you properly encapsulate your graph (and/or use it smartly) you can avoid this.

  3. The Following User Says Thank You to helloworld922 For This Useful Post:

    6Sloth9 (May 1st, 2011)

  4. #3
    Administrator copeg's Avatar
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    Default Re: Should i use a hashmap?

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