Thread: Populate an Object with Other Objects

I am using inheritance in a pretty standard exercise here.

I have a Card class and then a few classes that extend the Card class of different Card Types.

I however have a different type of class that still extends my Card class but is dealing with a LinkedList.

I have all of this accomplished, however in the exercise, there is a step that states "Have a main() method populate a Billfold object with Card objects, and then call
printCards()."


Here is the BillFold class.

import java.util.*;
 
public class Billfold extends Card
{
	LinkedList<Card> cards;
 
	Card firstCard;
	Billfold billf;
 
 
	public static void main(String[] args)
	{
 
		billf = new Billfold();
 
		printCards();
	}
 
 
	public Billfold()
	{
 
		cards = new LinkedList<Card>();
 
 
	}
 
 
	public void addCard(Card newCard)
	{
		if(firstCard == null)
			firstCard = newCard;
		else
			cards.add(newCard);
	}
 
	public void printCards()
	{
		for(int i = 0; i < cards.size(); i++)
		{
 
			if(cards.get(i) != null)
			{
				super.print();
			}
		}
	}
}

And then here is the original Card class BillFold is extending

   import java.util.*;
   import java.io.*;
 
 
   public class Card
   {
      private String name;
      private Card nextCard;
 
		public Card()
      {
         name = "";
      }
      public Card(String n)
      {
         name = n;
      }
      public Card getNext()
      {
         return nextCard;
      }
      public boolean isExpired()
      {
         return false;
      }
      public void print()
      {
         System.out.println("Card holder: " + name);
      }
      public void setNext(Card c)
      {
         nextCard = c;
      }
 
   }

So my question is: What does it mean to populate a Billfold object with Card objects in my Billfold Class?

*Don't be confused by my inheritance info, this question is not about inheritance.

Thanks in advance.