fruitmachine.java

J2ME MIDP_Example_Applications

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package example.fruitmachine;

import java.util.*;


class FruitMachine 
{
    static class InvalidPlayException
        extends Exception
    {
        InvalidPlayException(String message)
        {
            super(message);
        }
    }


    static class SpinResult
    {
        private int wheel[] = new int[3];
        private boolean win;
        private int winAmount;
    
    
        SpinResult(int[] wheel, boolean win, int winAmount)
        {
            this.wheel[0] = wheel[0];
            this.wheel[1] = wheel[1];
            this.wheel[2] = wheel[2];
            this.win = win;
            this.winAmount = winAmount;
        }
    
    
        int getWheel(int i)
        {
            return wheel[i];
        }
    
    
        boolean isWin()
        {
            return win;
        }
    
    
        int getWinAmount()
        {
            return winAmount;
        }
    }


    private static final int BAR = 0;
    private static final int BELL = 1;
    private static final int ORANGE = 2;
    private static final int LEMON = 3;
    private static final int PLUM = 4;
    private static final int CHERRY = 5;

    private static String names[] =
    {
        "bar", "bell", "orange", "lemon", "plum", "cherry"
    };
    private static final int wheelValues[] =
    {
        BAR, ORANGE, LEMON, PLUM, CHERRY,
        BELL, ORANGE, LEMON, PLUM, CHERRY,
        BELL, ORANGE, LEMON, PLUM, CHERRY,
        BELL, ORANGE, LEMON, PLUM, CHERRY
    };
    
    private int[] lastWheel = new int[3];
    private boolean[] lastHold = new boolean[3];
    private int lastBet = 0;
    private boolean lastWin = false;
    private Random random = new Random();
    private static final int HOUSE_LIMIT = 100;
    // These next values were found by experiment to allow the smartest
    // player to win back on average 96% of what they bet :-)
    private static final int THREE_BAR_WIN = 30;
    private static final int THREE_BELL_WIN = 10;
    private static final int THREE_OTHER_WIN = 5;

    private User user;   // so we can charge and credit their account


    FruitMachine(User user)
    {
        this.user = user;
    }


    // There's a subtle constraint here: in the first spin, we will never
    // allow a hold, since we start with no holds and lastBet=0. They must
    // increase the bet to at least 1, and if they increase the bet they
    // can't add a hold. Therefore, we don't have to initialize the
    // lastWheel values before the first spin - they can never be used.
    // This method is synchronized to protect us from strange effects if
    // a hacker tries to run several clients with the same session ID
    synchronized SpinResult spin(int bet,
                                 boolean hold0,
                                 boolean hold1,
                                 boolean hold2)
        throws InvalidPlayException
    {
        // you can't have a negative or zero bet
        if (bet <= 0)
        {
            throw new InvalidPlayException(
                "You must bet at least 1 credit");
        }

        // you can't bet more than HOUSE_LIMIT
        if (bet > HOUSE_LIMIT)
        {
            throw new InvalidPlayException(
                "House limit is " + HOUSE_LIMIT + " credits");
        }

        // if you add a hold, you can't increase your bet (the client
        // should not allow this, but we don't trust the client :-)
        if (((hold0 && !lastHold[0]) ||
             (hold1 && !lastHold[1]) ||
             (hold2 && !lastHold[2])) && (bet > lastBet))
        {
            throw new InvalidPlayException(
                "If you hold more wheels, you can't increase your bet");
        }

        // you can't hold any part of a winning set of wheels (the client
        // should not allow this, but we don't trust the client :-)
        if (lastWin && (hold0 || hold1 || hold2))
        {
            throw new InvalidPlayException(
                "You can't hold from a win");
        }

        //*** START REALLY-SHOULD-BE-TRANSACTION
        // charge their account for the bet; complain if there wasn't
        // enough credit
        if (!user.deductCredit(bet))
        {
            throw new InvalidPlayException(
                "Not enough credit for this bet");
        }

        lastBet = bet;
        lastHold[0] = hold0;
        lastHold[1] = hold1;
        lastHold[2] = hold2;
        for (int i = 0; i < lastHold.length; ++i)
        {
            if (!lastHold[i])
            {
                lastWheel[i] = random.nextInt(wheelValues.length);
            }
        }

        // check for a win
        lastWin = false;
        int winAmount = 0;
        if ((wheelValues[lastWheel[0]] == BAR) &&
            (wheelValues[lastWheel[1]] == BAR) &&
            (wheelValues[lastWheel[2]] == BAR))
        {
            lastWin = true;
            winAmount = THREE_BAR_WIN * lastBet;
        }
        else if ((wheelValues[lastWheel[0]] == BELL) &&
                 (wheelValues[lastWheel[1]] == BELL) &&
                 (wheelValues[lastWheel[2]] == BELL))
        {
            lastWin = true;
            winAmount = THREE_BELL_WIN * lastBet;
        }
        else if ((wheelValues[lastWheel[0]] == wheelValues[lastWheel[1]]) &&
                 (wheelValues[lastWheel[1]] == wheelValues[lastWheel[2]]))
        {
            lastWin = true;
            winAmount = THREE_OTHER_WIN * lastBet;
        }
        user.addCredit(winAmount);
        //*** END REALLY-SHOULD-BE-TRANSACTION

        return new SpinResult(lastWheel, lastWin, winAmount);
    }
}