ATM class

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

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

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

    public void run()
    {
        while (true)
        {
            while( !userAuthenticated )
            {
                screen.displayMessageLine( "\nSelamat Datang!");
                authenticateUser();
            }

            performTransactions();
            userAuthenticated = false;
            currentAccountNumber = 0;

        }
    }

    private void authenticateUser()
    {
        screen.displayMessage("\nMasukkan Nomor Akun Anda: " );
        int accountNumber = keypad.getInput();
        screen.displayMessage("\nMasukkan PIN Anda: " );
        int pin = keypad.getInput();

        userAuthenticated = bankDatabase.authenticateUser( accountNumber, pin );

        if ( userAuthenticated )
        {
            currentAccountNumber = accountNumber;
        }
        else
        {
            screen.displayMessageLine( "Nomor Akun atau PIN anda SALAH. Silahkan coba lagi!" );
        }
    }

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

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

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

                currentTransaction = createTransaction( mainMenuSelection );
                currentTransaction.execute();
                break;

                case EXIT:
                screen.displayMessageLine( "\n Keluar Dari System. . ." );
                userExited = true;
                break;
                default:
                screen.displayMessageLine( "\nAnda Tidak Memasukan Angka dengan Tepat. Silahkan Coba Sekali Lagi!" );
                break;
            }
        }
    }

    private int displayMainMenu()
    {
        screen.displayMessageLine( "\nMain Menu:" );
        screen.displayMessageLine( "1. Melihat Saldo" );
        screen.displayMessageLine( "2. Tarik Tunai" );
        screen.displayMessageLine( "3. Menyimpan Uang" );
        screen.displayMessageLine( "4. EXIT\n" );
        screen.displayMessageLine( "Masukan Pilihan Anda! " );
        return keypad.getInput();
    }

    private Transaction createTransaction( int type )
    {
        Transaction temp = null;

        switch ( type )
        {
            case BALANCE_INQUIRY:
            temp = new BalanceInquiry( currentAccountNumber, screen, bankDatabase );
            break;
            case WITHDRAW:
            temp = new Withdraw( currentAccountNumber, screen, bankDatabase, keypad, cashDispenser );
            break;
            case DEPOSIT:
            temp = new Deposit( currentAccountNumber, screen,bankDatabase, keypad, depositSlot );
            break;
        }
        return temp;
    }
}