Hierarchical data structure

Question

I am trying to represent the following data structure in hierarchical format ---- but I am not going to use any swing components, so jtree and such are out, and xml is probably out. I was hoping some form of collection would work but I can't seem to get it!
Example Scenario
Football League --- Football Team -- Player Name
West
------------------------------Chiefs
-------------------------------------------------------------xyz
-------------------------------------------------------------abc
-------------------------------------------------------------mno
------------------------------Broncos
------------------------------------------------------------asq
------------------------------------------------------------daff
This hierarchical structure has a couple of layers, so I don't know how I can feasibly do it. I have tried to look at making hashmaps on top of each other so that as I iterate thru the data, I can check for the existence of a key, and if it exists, get the key and add to it.
Does anyone know a good way to do this? Code samples would be appreciated!!!
Thank you!

Answer 1

Hi Jason,
I guess you wouldn't want to use Swing components or JTree unless your app has some GUI and even then you would want to look for some other structure than say JTree to represent your data.
You have got plenty options one is that of using nested HashMaps. You could just as well use nested Lists or Arrays or custom objects that represent your data structure.
I don't know why you should exclude XML. There is the question anyway how you get your data in your application. Is a database the source or a text file? Why not use XML since your data seems to have a tree structure anyway and XML seems to fit the bill.
An issue to consider in that case is the amount of data. Large XML files have performance problems associated with them.
In terms of a nice design I would probably do something like this (assuming the structure of your data is fixed):
public class Leagues {
    private List leagues = new ArrayList();
    public FootballLeague getLeagueByIndex(int index) {
        return (FootballLeague)leagues.get(index);
    public FootballLeague getLeagueByName(String name) {
        // code that runs through the league list picking out the league with the given name
    public void addLeague(FootballLeague l) {
        leagues.add( l );
}Next you define a class called FootballLeague:
public class FootballLeague {
    private List teams = new ArrayList();
    private String leagueName;
    public FootballTeam getTeamByIndex(int index) {
        return (FootballTeam)teams.get( index );
    public FootballTeam getTeamByName(String name) {
        // code that runs through the team list picking out the team with the given name
    public void addTeam(FootballTeam t) {
        teams.add( t );
    public void setTeamName(String newName) {
        this.name = newName;
    public String getTeamName() {
        return this.name;
}Obviously you will continue defining classes for Players next following that pattern. I usually apply that kind of structure for complex hierarchical data. Nested lists would be just as fine, but dealing with nested lists rather than a simple API for you data structures can be a pain (especially if you have many levels in your hierarchy);
Hope that helps.
The Dude