Iterate through fields in an Inner Class

[Dieter Stryker]

Hi,

I have a TreeMap which contains Team objects.

Inside each Team instance is an ArrayList<Game> - Game is an inner class of Team

How do I iterate through the data structure so I can access the fields in each Game in the ArrayList of a Team

I don't know how to code this.

[K. Tsang]

Hi there, I'm not sure if this works or not. You know how to iterator through a map right? Ultimately once you get the Team object, you need an iterator inside the Team object to iterate throught the Game object.

Now the problem is what type of object is Team? If it is some kind of collection then it's easy. If not, is making it into a collection a possible solution?

Another approach is instead of using ArrayList<Game> you use your own collection that extends ArrayList. Then in it you call your iterator in your custom collection to iterate Game.

Hope this helps.

[Dieter Stryker]

K. Tsang wrote:Hi there, I'm not sure if this works or not. You know how to iterator through a map right? Ultimately once you get the Team object, you need an iterator inside the Team object to iterate throught the Game object.

Now the problem is what type of object is Team? If it is some kind of collection then it's easy. If not, is making it into a collection a possible solution?

Another approach is instead of using ArrayList<Game> you use your own collection that extends ArrayList. Then in it you call your iterator in your custom collection to iterate Game.

Hope this helps.

Does this look correct:

 	Document buildScoresXML(TreeMap teamMap)
	throws Exception
	{	
		Document xmlDoc = new DocumentImpl();
		
		// create root element
		Element rootElement = xmlDoc.createElement("lacrosse"); //has children
		xmlDoc.appendChild(rootElement);
		
		Element title = xmlDoc.createElement("title");
		rootElement.appendChild(title);
		title.appendChild(xmlDoc.createTextNode("College Lacrosse Results"));

		//to process TreeMap teamMap 
		Collection teamCollection = teamMap.values();
		Iterator teamIterator = teamCollection.iterator();		
		
		while (teamIterator.hasNext())
		{
			// process current team in TreeMap
			Team currentTeam = (Team) teamIterator.next();
			
			// create team element
			Element team = xmlDoc.createElement("team");
			rootElement.appendChild(team);
			team.appendChild(xmlDoc.createTextNode(currentTeam.getName()));
			
			// create wins element
			Element wins = xmlDoc.createElement("wins");
			team.appendChild(wins);
			wins.appendChild(xmlDoc.createTextNode(toString(currentTeam.getWins())));
			
			// create losses element
			Element losses = xmlDoc.createElement("losses");
			team.appendChild(losses);
			losses.appendChild(xmlDoc.createTextNode(toString(currentTeam.getLosses())));
			
			// to process ArrayList games
			while (((Iterator) currentTeam.game).hasNext()); 
			{
				// create opponent element
				Element opponent = xmlDoc.createElement("opponent");
				team.appendChild(opponent);
				opponent.appendChild(xmlDoc.createTextNode(currentTeam.game.getOpponentName()));
			
				// create element location
				Element location = xmlDoc.createElement("location");
				opponent.appendChild(location);
				opponent.appendChild(xmlDoc.createTextNode(currentTeam.game.getLocation()));
				
				// create element for
				Element goalsFor = xmlDoc.createElement("for");
				opponent.appendChild(goalsFor);
				opponent.appendChild(xmlDoc.createTextNode(toString(currentTeam.game.getGoalsScored())));
				
				Element against = xmlDoc.createElement("against");
				opponent.appendChild(against);
				opponent.appendChild(xmlDoc.createTextNode(toString(currentTeam.game.getGoalsAllowed())));   

EDIT -- My Team class is:

 import java.util.ArrayList;
import java.util.Iterator;


/**
 * Object class for interim storage of db information to be used
 * from collection to generation of xml
 * 
 * @author kwegner83
 *
 */
public class Team 
{
	private String location;	
	private String teamName;
	private int wins = 0;
	private int losses = 0;
	ArrayList<Game> games = new ArrayList<Game>();
	Game game = null;

	
	public Team(String name)
	{
		this.teamName = name;
	}
	
	public void addGame(String opponentName, String location, int goalsScored, int goalsAllowed)
	{
		games.add(new Game(opponentName, location, goalsScored, goalsAllowed));
	}
	
	public String getName()
	{
		return teamName;
	}
	
	public int getWins()
	{
		return wins;
	}
	
	public void addWin()
	{
		wins = wins + 1;
	}
	
	public int getLosses()
	{
		return losses;
	}
	
	public void addLoss()
	{
		losses = losses + 1;
	}
	
	public boolean equals(Object team)
	{
		return ((Team)team).getName().equals(teamName);
	}
	
	class Game
	{
		private String opponentName;
		private String location;
		private int goalsScored = 0;
		private int goalsAllowed = 0;
	
		//constructor
		public Game(String opponentsName, String location, int goalsScored, int goalsAllowed)
		{
			this.opponentName = opponentsName;
			this.location = location;
			this.goalsScored = goalsScored;
			this.goalsAllowed = goalsAllowed;
		}

		public String getOpponentName() { return opponentName; }
		public String getLocation() { return location; }
		public int getGoalsScored() { return goalsScored; }
		public int getGoalsAllowed() { return goalsAllowed; }
		
	} // inner class Game
} // class Team
   

[Ankit Garg]

Dieter, you'll need to make the Game class in Team class as public. Secondly, you don't need the Game object inside the Team class i.e. this statement

19. Game game = null;

And you'll need to encapsulate the games list i.e. generate a getGames method in your Team class that will return the games ArrayList. Then instead of this statement

while (((Iterator) currentTeam.game).hasNext());

You'll have to write

Iterator<Game> gameIterator = currentTeam.getGames().iterator();
while(gameIterator.hasNext()) {
         //some logic
}

And remember never to use this kind of syntax

while(list.getIterator().hasNext())

That way a new iterator will be created everytime so the loop will continue iterating over the first element infinitely...

[K. Tsang]

Based on your current approach, Ankit is right - your Game class can be public. In fact Team and Game are 2 different things so why not Game public.

Now if Game is public there shouldn't be any problem because you are not trying to access some inner class thing.

I also noticed your Game class is immutable (eg not set methods). Nice.

[Keith R Wegner]

K. Tsang wrote:Based on your current approach, Ankit is right - your Game class can be public. In fact Team and Game are 2 different things so why not Game public.

Now if Game is public there shouldn't be any problem because you are not trying to access some inner class thing.

I also noticed your Game class is immutable (eg not set methods). Nice.

Thanks to both of you.

I was up pretty late trying to code this and was probably suffering from sleep deprivation more than anything. I've made the appropriate changes and am moving forward nicely.

Thanks for the feedback.