class LinkList
   {
   private Link first;            // ref to first link on list
   private int numLinks;	  // keeps track of the number of
				  // links in thte linked list

// -------------------------------------------------------------
   public LinkList()              // constructor
      {
      first = null;               // no links on list yet
      numLinks = 0;
      }
// -------------------------------------------------------------
   public void insertFirst(int id, double dd)
      {                           // make new link
      Link newLink = new Link(id, dd);
      newLink.next = first;       // it points to old first link
      first = newLink;            // now first points to this
      numLinks++;
      }
// -------------------------------------------------------------
// Function is modified to handle empty linked lists
   public Link find(int key)      // find link with given key
      {                           
      // If list is empty return null
      if(first == null)
	 return null;

      Link current = first;              // start at 'first'
      while(current.iData != key)        // while no match,
         {
         if(current.next == null)        // if end of list,
            return null;                 // didn't find it
         else                            // not end of list,
            current = current.next;      // go to next link
         }
      return current;                    // found it
      }
// -------------------------------------------------------------
// Function is modified to handle empty linked lists
   public Link delete(int key)    // delete link with given key
      {                           

      // If list is empty return null
      if(first == null)
         return null;
	  
      Link current = first;              // search for link
      Link previous = first;
      while(current.iData != key)
         {
         if(current.next == null)
            return null;                 // didn't find it
         else
            {
            previous = current;          // go to next link
            current = current.next;
            }
         }                               // found it

      numLinks--;
      if(current == first)               // if first link,
         first = first.next;             //    change first
      else                               // otherwise,
         previous.next = current.next;   //    bypass it
      return current;
      }
// -------------------------------------------------------------
   public void displayList()      // display the list
      {
      System.out.print("List (first-->last): ");
      Link current = first;       // start at beginning of list
      while(current != null)      // until end of list,
         {
         current.displayLink();   // print data
         current = current.next;  // move to next link
         }
      System.out.println("");
      }
// -------------------------------------------------------------
// New function: returns true iff linked list is empty
   public boolean isEmpty()
      {
	 return numLinks == 0;
      }
// -------------------------------------------------------------
// New function: returns the size of the linked list
   public int size()
      {
         return numLinks;
      }
// -------------------------------------------------------------
// New function: copies the int data stored in the Link objects 
// of the LinkList into an int array and returns tha array.
   public int[] toArray()
   {
	int[] temp = new int[numLinks];

	Link current = first;
	int i = 0;
        while(current != null)
	{
		temp[i++] = current.iData;
		current =  current.next;
	}

	return temp;
			
    }

}  // end class LinkList