Lottery Configuration

public abstract class Lottery {

    private final LotteryPrize prize; // custom object can be a coupon, can be merchant aparell, merchandise

    private int numberOfWinners;
    private List<Customer> participants;

    private Date endTime;

    private LotteryWinnerChooser chooser;
    private LotteryPrizeAwarder awarder;
    private LotteryAnnouncer announcer;


    public abstract void addParticipant(Customer participant);
    public abstract void announceSelf();
    public abstract void awardPrize();

}

public interface LotteryWinnerChooser {

    /**
     * Chooses a subset of the provided participants of the provided number
     * and returns them as the winners.
     */
    public List<Customer> getWinners(List<Customer> participants, int numberOfWinners);

}

public interface LotteryPrizeAwarder {

    /**
     * Provides a way to all winners to collect their prize.
     */
    public void award(LotteryPrize prize, List<Customer> winners);

}

public interface LotteryAnnouncer {

    /**
     * Announces the lottery to potential participants.
     */
    public void announce(Lottery lottery);

}