A return int method problem

[Andrew Parker]

Hi,
Here is the code:

main class:
System.out.println(x.CardsUndrawn());
public class x:
public int drawn()
  {
     int a = yo.getSize(); //yo is an object of class y
     return a;
  }
public class y: //class y is a linkedlist
  public int getSize()
  {
    LinkedListItr itr = zeroth( );
    int i = 0;
    for  ( ; !itr.isListEnd( ); itr.advance( ) ){
      i++;
    }
    return i;
  }
  public LinkedListItr zeroth( )
  {
    return new LinkedListItr( header );
  }

public class LinkedListItr
{
    ListNode current;    // Current position
    /**
     * Construct the list iterator
     * @param theNode any node in the linked list.
     */
    LinkedListItr(ListNode theNode)
    {
        current = theNode;
    }
    /**
     * Test if the current position is past the end of the list.
     * @return true if the current position is null.
     */
    public boolean isPastEnd( )
    {
        return current == null;
    }
    public boolean isListEnd( )
   {
        return current.next == null;
    }
    /**
     * Return the item stored in the current position.
     * @return the stored item or null if the current position
     * is not in the list.
     */
    public Object retrieve( )
    {
        return isPastEnd( ) ? null : current.data;
    }
    /**
     * Advance the current position to the next node in the list.
     * If the current position is null, then do nothing.
     */
    public void advance( )
    {
        if( !isPastEnd( ) )
            current = current.next;
    }
}

It throws Exception when I make it. Why yo.getSize() cannot return an int?
Any idea?
Thanks

[Andrew Parker]

sorry, it should be public int CardsUndrawn()

[Layne Lund]

What exception is thrown exactly? I don't see anything wrong off the top of my head. Also, which line throws the exception?
If you can give these details, then we can more easily help you find the solution to your problem.
Layne

[William Barnes]

Did you not post all the code?

 
public LinkedListItr zeroth( )
{
  return new LinkedListItr( header );
}  

What is "header"?
You constructor for LinkedListItr assumes that "theNode" is not null. Which in this case may be the case.
Than when you test in "isListEnd()" you once again are not testing to ensure that "current" is not null, which I think may be your problem.