public class Withdrawal extends Transaction
{
    private int amount;
    private Keypad keypad;
    private CashDispenser cashDispenser;

    private final static int CANCELED = 6;

    public Withdrawal( int userAccountNumber, Screen atmScreen,
        BankDatabase atmBankDatabase, Keypad atmKeypad,
        CashDispenser atmCashDispenser )
    {
        super( userAccountNumber, atmScreen, atmBankDatabase );

        keypad = atmKeypad;
        cashDispenser = atmCashDispenser;
    }

    @Override
    public void execute()
    {
        boolean cashDispensed = false;
        double availableBalance;

        BankDatabase bankDatabase = getBankDatabase();
        Screen screen = getScreen();

        do
        {
            amount = displayMenuOfAmounts();

            if ( amount != CANCELED )
            {
                availableBalance = bankDatabase.getAvailableBalance( getAccountNumber() );

                if ( amount <= availableBalance )
                {
                    if ( cashDispenser.isSufficientCashAvailable( amount ) )
                    {
                        bankDatabase.debit( getAccountNumber(), amount );

                        cashDispenser.dispenseCash( amount );
                        cashDispensed = true;

                        screen.displayMessageLine( "\nYour cash has been" +
                            " dispensed. Please take your cash now." );
                    }
                    else
                        screen.displayMessageLine(
                            "\nInsufficient cash available in the ATM." +
                            "\n\nPlease choose a smaller amount." );
                }
                else
                {
                    screen.displayMessageLine(
                        "\nInsufficient funds in your account." +
                        "\n\nPlease choose a smaller amount." );
                }
            }
            else
            {
                screen.displayMessageLine( "\nCanceling transaction..." );
                return;
            }
        } while ( !cashDispensed );
    }

    private int displayMenuOfAmounts()
    {
        int userChoice = 0;

        Screen screen = getScreen();

        int[] amounts = { 0, 20, 40, 60, 100, 200 };

        while ( userChoice == 0 )
        {
            screen.displayMessageLine( "\nWithdrawal Menu:" );
            screen.displayMessageLine( "1 - $20" );
            screen.displayMessageLine( "2 - $40" );
            screen.displayMessageLine( "3 - $60" );
            screen.displayMessageLine( "4 - $100" );
            screen.displayMessageLine( "5 - $200" );
            screen.displayMessageLine( "6 - Cancel transaction" );
            screen.displayMessage( "\nChoose a withdrawal amount: " );

            int input = keypad.getInput();

            switch ( input )
            {
                case 1:
                case 2:
                case 3:
                case 4:
                case 5:
                    userChoice = amounts[ input ];
                    break;
                case CANCELED:
                    userChoice = CANCELED;
                    break;
                default:
                    screen.displayMessageLine( "\nInvalid selection. Try again." );
            }
        }

        return userChoice;
    }
}