Grouping objects - Objects First with Java: A Practical Introduction Using BlueJ - page 132

Code 4.10
The Auction class

import java.util.ArrayList;
/**
* A simple model of an auction.
* The auction maintains a list of lots of arbitrary length.
* @author David J. Barnes and Michael Kölling.
* @version 2011.07.31
*/
public class Auction
{
// The list of Lots in this auction.
private ArrayList<Lot> lots;
// The number that will be given to the next lot entered
// into this auction.
private int nextLotNumber;

/**
* Create a new auction.
*/
public Auction()
{

lots = new ArrayList<Lot>();
nextLotNumber = 1;

}

/**
* Enter a new lot into the auction.
* @param description A description of the lot.
*/
public void enterLot(String description)
{

lots.add( new Lot(nextLotNumber, description));
nextLotNumber++;

}

/**
* Show the full list of lots in this auction.
*/
public void showLots()
{

for (Lot lot : lots) {
System.out.println(lot.toString());

}

}

/**
* Make a bid for a lot.
* A message is printed indicating whether the bid is
* successful or not.