public class StockItem implements java.lang.Comparable {
  public String title;
  private int have, want;
  private ListReferenceBased waitingList;
   
  // various constructors for StockItem

  public void addToWaitingList(String lastName, String firstName, String phone) {
  // add a person to the waiting list
    waitingList.addSorted(
                 new Customer(lastName, firstName, phone));
  } // end addToWaitingList

  public String toString() {
    // for displaying StockItem instances
    return null;
  } // end toString

  public int compareTo(Object rhs) {
  // define how StockItems are compared
     return title.compareTo(((StockItem)rhs).title);
  } // end compareTo

// mutator and accessor methods for other data fields

}  // end class StockItem