ATM

public class ATM
{
    private boolean userAuthenticated;
    private int currentAccountNumber;
    private Screen screen;
    private Keypad keypad;
    private CashDispenser cashDispenser;
    private BankDatabase bankDatabase;


    private static final int BALANCE_INQUIRY = 1;
    private static final int WITHDRAWAL = 2;
    private static final int DEPOSIT = 3;
    private static final int EXIT = 4;

    public ATM()
    {
        userAuthenticated = false;
        currentAccountNumber = 0;
        Screen screen = new Screen();
        Keypad keypad = new Keypad();
        CashDispenser cashDispenser = new CashDispenser();
        BankDatabase bankDatabase = new BankDatabase();
    }

    public void run()
    {
        while(true)
        {
            while(!userAuthenticated)
            {
                screen.displayMessage("\nWelcome!");
                authenticateUser();
            }

            performTransactions();
            userAuthenticated = false;
            currentAccountNumber = 0;
            scren.displayMessage("/nThank You!. Come Again!");
        }
    }

    private void authenticateUser()
    {
        screen.displayMessage("/nPlease enter your account number: ");
        int accountNumber = keypad.getInput();
        screen.displayMessage("/nPlease enter your PIN: ");
        int pin = keypad.getInput();

        userAuthenticated = bankDatabase.authenticateUser(accountNumber, pin);

        if(userAuthenticated)
        {
            currentAccountNumber = accountNumber;
        }

        else
        {
            screen.displayMessage("/nInvalid account or PIN. Please try again");
        }

    }

    private void performTransaction()
    {
        Transaction currentTransaction = null;
        boolean userExited = false;

        while(!userExited)
        {
            int mainMenuSelection = displayMainMenu();

            switch(mainMenuSelection)
            {
                case BALANCE_INQUIRY:
                case WITHDRAWAL:
                case DEPOSIT:

                    currentTransaction = createTransaction(mainMenuSelection);

                    currentTransaction.execute();
                    break;
                case EXIT:
                    screen.displayMessage("/nExiting system...");
                    userExited = true;
                    break;
                default:
                    screen.displayMessage("/nYou did not enter a valid selection. Try again.");
                    break;
                }
            }
        }

    private int displayMainMenu()
    {
      screen.displayMessageLine( "\nMain menu:" );
      screen.displayMessageLine( "1 - View my balance" );
      screen.displayMessageLine( "2 - Withdraw cash" );
      screen.displayMessageLine( "3 - Deposit funds" );
      screen.displayMessageLine( "4 - Exit\n" );
      screen.displayMessage( "Enter a choice: " );
      return keypad.getInput();
    }

    private Transaction createTransaction(int type)
    {
        Transaction temp = null;
        switch(type)
        {
            case BALANCE_INQUIRY:
                temp = new BalanceInquiry(currentAccountNumber, screen, bankDatabase);
                break;
            case WITHDRAWAL:
                temp = new Withdrawal(currentAccountNumber, screen, bankDatabase, keypad, cashDispenser);
                break;
            case DEPOSIT:
                temp = new Deposit(currentAccountNumber, screen, bankDatabase, keypad, depositSlot);
                break;
            }
            return temp;
        }

}