Withdrawal.java

/**
 * Represents a withdrawal ATM transaction
 */
public class Withdrawal extends Transaction {
    private int amount; // amount to withdraw
    private Keypad keypad; // reference to keypad
    private CashDispenser cashDispenser; // reference to cash dispenser

    // constant corresponding to menu option to cancel
    private final static int CANCELED = 6;

    // Withdrawal constructor
    public Withdrawal(int userAccountNumber, Screen atmScreen, BankDatabase atmBankDatabase, Keypad atmKeypad,
            CashDispenser atmCashDispenser) {
        // initialize superclass variables
        super(userAccountNumber, atmScreen, atmBankDatabase);

        // initialize references to keypad and cash dispenser
        keypad = atmKeypad;
        cashDispenser = atmCashDispenser;
    } // end Withdrawal constructor

    // perform transaction
    @Override
    public void execute() {
        boolean cashDispensed = false; // cash was not dispensed yet
        double availableBalance; // amount available for withdrawal

        // get references to bank database and screen
        BankDatabase bankDatabase = getBankDatabase();
        Screen screen = getScreen();

        // loop until cash is dispensed or the user cancels
        do {
            // obtain a chosen withdrawal amount from the user
            amount = displayMenuOfAmounts();

            // check whether user chose a withdrawal amount or canceled
            if (amount != CANCELED) {
                // get available balance of account involved
                availableBalance = bankDatabase.getAvailableBalance(getAccountNumber());

                // check whether the user has enough money in the account
                if (amount <= availableBalance) {
                    // check whether the cash dispenser has enough money
                    if (cashDispenser.isSufficientCashAvailable(amount)) {
                        // update the account involved to reflect the withdrawal
                        bankDatabase.debit(getAccountNumber(), amount);

                        cashDispenser.dispenseCash(amount); // dispense cash
                        cashDispensed = true; // cash was dispensed

                        // instruct user to take cash
                        screen.displayMessageLine("\nYour cash has been" + " dispensed. Please take your cash now.");
                    } // end if
                    else // cash dispenser does not have enough cash
                        screen.displayMessageLine(
                                "\nInsufficient cash available in the ATM." + "\n\nPlease choose a smaller amount.");
                } // end if
                else // not enough money available in user's account
                {
                    screen.displayMessageLine(
                            "\nInsufficient funds in your account." + "\n\nPlease choose a smaller amount.");
                } // end else
            } // end if
            else // user chose cancel menu option
            {
                screen.displayMessageLine("\nCanceling transaction...");
                return; // return to main menu because user canceled
            } // end else
        } while (!cashDispensed);

    } // end method execute

    // display a menu of withdrawal amounts and the option to cancel;
    // return the chosen amount or 0 if the user chooses to cancel
    private int displayMenuOfAmounts() {
        int userChoice = 0; // local variable to store return value

        Screen screen = getScreen(); // get screen reference

        // array of amounts to correspond to menu numbers
        int[] amounts = { 0, 20, 40, 60, 100, 200 };

        // loop while no valid choice has been made
        while (userChoice == 0) {
            // display the withdrawal menu
            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(); // get user input through keypad

            // determine how to proceed based on the input value
            switch (input) {
            case 1: // if the user chose a withdrawal amount
            case 2: // (i.e., chose option 1, 2, 3, 4 or 5), return the
            case 3: // corresponding amount from amounts array
            case 4:
            case 5:
                userChoice = amounts[input]; // save user's choice
                break;
            case CANCELED: // the user chose to cancel
                userChoice = CANCELED; // save user's choice
                break;
            default: // the user did not enter a value from 1-6
                screen.displayMessageLine("\nInvalid selection. Try again.");
            } // end switch
        } // end while

        return userChoice; // return withdrawal amount or CANCELED
    } // end method displayMenuOfAmounts
} // end class Withdrawal