ATMSimulator.java

import java.util.Scanner;

class BankAccount {
    private double balance;
    private final String accountNumber;
    private final String pin;

    public BankAccount(String accountNumber, double initialBalance, String pin) {
        this.accountNumber = accountNumber;
        this.balance = initialBalance;
        this.pin = pin;
    }

    public String getAccountNumber() {
        return this.accountNumber;
    }

    public boolean verifyPIN(String enteredPIN) {
        return this.pin.equals(enteredPIN);
    }

    public double getBalance() {
        return balance;
    }

    public void deposit(double amount) {
        if (amount > 0) {
            balance += amount;
            System.out.println("Successfully deposited:$" + amount);
        } else {
            System.out.println("Invalid deposit amount!");
        }
    }

    public void withdraw(double amount) {
        if (amount <= 0) {
            System.out.println("Invalid withdrawal amount!");
        } else if (amount > balance) {
            System.out.println("Error: Insufficient funds");
        } else {
            balance -= amount;
            System.out.println("Successfully withdrew: $" + amount);
        }
    }
}

public class ATMSimulator {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        BankAccount myAccount = new BankAccount("123456789", 500.0, "4321");
        System.out.println("=== Welcome to Java Bank ATM ===");
        int attempts = 3;
        boolean authenticated = false;

        while (attempts > 0) {
            System.out.print("Please enter your 4-digit PIN: ");
            String enteredPIN = scanner.next();

            if (myAccount.verifyPIN(enteredPIN)) {
                System.out.println("\nPIN Verified. Access Granted!");
                authenticated = true;
                break;
            } else {
                attempts--;
                System.out.println("Incorrect PIN. Attempts remaining: " + attempts);
            }
        }
        if (!authenticated) {
            System.out.println("\nToo many incorrect attempts. Your card has been blocked!");
            scanner.close();
            return;
        }
        boolean running = true;
        while (running) {
            System.out.println("\n--- MAIN MENU ---");
            System.out.println("1. Check Balance");
            System.out.println("2. Deposit Money");
            System.out.println("3. Withdraw Money");
            System.out.println("4. Exit");
            System.out.print("Choose an option (1-4): ");
            int choice = scanner.nextInt();
            switch (choice) {
                case 1:
                    System.out.println("Your current balance is: $" + myAccount.getBalance());
                    break;
                case 2:
                    System.out.print("Enter deposit amount: ");
                    double depAmount = scanner.nextDouble();
                    myAccount.deposit(depAmount);
                    break;
                case 3:
                    System.out.print("Enter withdrawal amount: ");
                    double drawAmount = scanner.nextDouble();
                    myAccount.withdraw(drawAmount);
                    break;
                case 4:
                    System.out.println("Thank you for using Java Bank ATM. Adios!");
                    running = false;
                    break;
                default:
                    System.out.println("Invalid option. Please try again.");
            }
        }
        scanner.close();
    }
}