Code Explanation

Below is the summary of the code’s main elements:

AtmLogin.java : This is the primary starting point for atm users. It shows a login screen for customers to enter their account number and PIN and verifies their credentials against database.

public void actionPerformed(ActionEvent e) {

String acc = txt_acc.getText();

String pin = txt_pin.getText();

String query = "SELECT * FROM atm WHERE acc_no = '"+acc+"' AND pin =

'"+pin+"'";

// If match found, redirect to ATMMainMenu

}

Create account.java : This files handles account creation of new customers. It collects user data through form fields and stores them in the account table in database.

String query = "INSERT INTO accounts (name, address, balance) VALUES (?, ?, ?)";

PreparedStatement ps = conn.prepareStatement(query);

ps.setString(1, name);

ps.setString(2, address);

ps.setDouble(3, initialDeposit);

ps.executeUpdate();

DBConnection.java :Uses JDBC to handle database connectivity. This class is reused across the app for all SQL queries.

public class DBConnection {

public static Connection getConnection() throws SQLException {

return DriverManager.getConnection("jdbc:mysql://localhost:3306/bankdb", "root",

"");

}

}

ATMMainMenu.java : Shows the main menu for ATM users and connects buttons to actions (withdrawal , deposits , mini statement , change pin etc).

JButton withdrawBtn = new JButton("Withdraw");

withdrawBtn.addActionListener(e -> new Withdraw(acc_no).setVisible(true));

Withdraw.java , Deposit,java , Transfer.java : Each of these files deals specifically with a transaction type , construct a custom window with Swing Components and then update the change to the account balance in the database.

String query = "UPDATE accounts SET balance = balance - ? WHERE acc_no = ?";

PreparedStatement ps = conn.prepareStatement(query);

ps.setDouble(1, amount);

ps.setString(2, acc_no);

ps.executeUpdate();

MiniStatement.java : Retrieves and displays the last n transactions of an account and is implemented using table components.

String query = "SELECT * FROM transactions WHERE acc_no = ? ORDER BY date DESC

LIMIT 5”;

changePin.java : Allows users to change their ATM PIN securely after verification.

String query = "UPDATE atm SET pin = ? WHERE acc_no = ?";

EmployeeLogin.java , employeeDashboard.java : Only bank employees use these two

classes to : login , create customer accounts , activate ATM access , process customer

deposits/withdrawal.

AdminLogin.java , AdminDashboard.java : Used by admin users to add or remove emplyoees , view all transaction , export data and view system usage.EmailSender.java : Sends confirmation and/or alert emails upon account creation or large transactions using JavaMail API

Properties props = new Properties();

props.put("mail.smtp.host", "smtp.gmail.com");

props.put("mail.smtp.port", "587");

...

Transport.send(message);