public class Deposit extends Transaction
{
    private double amount;      // amount to deposit
    private Keypad keypad;      // references to keypad
    private DepositSlot depositSlot;    // references to deposit slot
    private final static int CANCELED = 0;  // constant for cancel option

    // Deposit constructor
    public Deposit(int userAccountNumber, Screen atmScreen, BankDatabase atmBankDatabase, Keypad atmKeypad, DepositSlot atmDepositSlot){
        // initializes superclass variables
        super(userAccountNumber, atmScreen, atmBankDatabase);

        // initialize references to keypad and deposit slot
        keypad = atmKeypad;
        depositSlot = atmDepositSlot;
    }   // end Deposit constructor

    // perform transaction
    @Override
    public void execute(){
        BankDatabase bankDatabase = getBankDatabase();      // get reference
        Screen screen = getScreen();        // get reference

        amount = promptForDepositAmount();  // get deposit amount from user

        // check whether the user entered a deposit amount or canceled
        if(amount != CANCELED){
            // request deposit envelope containing specified amount
            screen.displayMessage("\nPlease insert a deposit envelope containing ");
            screen.displayDollarAmount(amount);
            screen.displayMessage(".");

            // receive deposit envelope
            boolean envelopeReceived = depositSlot.isEnvelopeReceived();

            // check whether deposit envelope was received
            if(envelopeReceived){
                screen.displayMessageLine("\nYour envelope has been received.");
                screen.displayMessage("NOTE: The money just deposited will not be available until we verify the amount");
                screen.displayMessage("of any enclosed cash and your checks clear.");

                // credit account to reflect the deposit
                bankDatabase.credit(getAccountNumber(), amount);
            }   // end if
            else{
                // deposit envelope not received
                screen.displayMessageLine("\nYou did not insert an envelope");
                screen.displayMessageLine("So, the ATM has canceled your transaction.");
            }   // end else
        }   // end if
        else{
            // user canceled instead of entering amount
            screen.displayMessageLine("\nCanceling transaction...");
        }   // end else
    }   // end method execute

    // prompt user to enter a deposit amount in cents
    private double promptForDepositAmount(){
        Screen screen = getScreen();    // get references to screen

        // display the prompt
        screen.displayMessage("\nPlease enter a deposit amount in CENTS (or 0 to cancel)");
        int input = keypad.getInput();  // receive input of deposit amount

        // check whether the user canceled or entered a valid amount
        if(input == CANCELED) return CANCELED;
        else{
            return (double) input / 100;        // return dollar amount
        }   // end else
    }   // end method
}   // end class Deposit