ATM CLI Simulation

A comprehensive ATM (Automated Teller Machine) simulation built in Java with OOP principles.

Features

Core Banking Operations

• Account Management: Create new accounts with secure PIN authentication
• Login System: Secure login with PIN verification
• Balance Management: Check account balance and debt information
• Deposit: Add money to your account
• Withdraw: Remove money from your account (with insufficient funds protection)
• Transfer: Send money between accounts (with debt tracking for insufficient funds)

Advanced Features

• Transaction History: Complete transaction logging and viewing
• Debt Management: Automatic debt tracking when transferring more than available balance
• Multiple Account Support: Support for multiple users
• Secure Authentication: PIN-based authentication system

Transaction History Features

• View recent transactions (last 10)
• View all transaction history
• Filter transactions by type (Deposit, Withdraw, Transfer In, Transfer Out)
• Filter transactions by date
• Detailed transaction information with timestamps

System Requirements

• Java 8 or higher
• Command line interface (Terminal/Command Prompt)

Installation and Setup

1. Clone or Download the Project

# If using Git
git clone <repository-url>
cd atm-cli

# Or download and extract the ZIP file

2. Navigate to Source Directory

cd src

3. Compile the Java Files

javac *.java

4. Run the Application

java ATMSimulation

Usage Instructions

Getting Started

1. Start the Application

   java ATMSimulation

2. Main Login Screen Options

   • 1. Login - Login to existing account
   • 2. Create Account - Create new account
   • 3. View Available Accounts - See all registered accounts
   • 4. Exit - Exit the application

Creating a New Account

1. Select option 2 from the main menu
2. Enter your desired username
3. Create a 4-digit PIN (numbers only)
4. Confirm your PIN
5. Account will be created successfully

PIN Requirements:

• Must be exactly 4 digits
• Can only contain numbers (0-9)
• Must match confirmation

Logging In

1. Select option 1 from the main menu
2. Enter your username
3. Enter your 4-digit PIN
4. If credentials are correct, you'll access the main banking menu

Banking Operations

Once logged in, you'll see the main banking menu:

1. Deposit Money

• Select option 1
• Enter the amount to deposit
• Money will be added to your account
• Transaction will be recorded in history

2. Withdraw Money

• Select option 2
• Enter the amount to withdraw
• System will check if you have sufficient funds
• If successful, money will be deducted and transaction recorded

3. Transfer Money

• Select option 3
• Enter the target account name
• Enter the amount to transfer
• If you have sufficient funds, full amount will be transferred
• If insufficient funds, partial transfer will occur with debt tracking

4. Transaction History

• Select option 5 to enter transaction history menu
• Submenu Options:
  • 1. Show Recent Transactions - View last 10 transactions
  • 2. Show All Transactions - View complete transaction history
  • 3. Filter by Transaction Type - Filter by Deposit/Withdraw/Transfer
  • 4. Filter by Date - Filter by specific date (DD/MM/YYYY format)
  • 5. Back to Main Menu - Return to banking menu

5. Logout

• Select option 6
• Safely logout and return to main login screen

Error Handling

The system includes comprehensive error handling for:

• Invalid PIN: Wrong PIN during login
• Account Not Found: Attempting to login with non-existent account
• Insufficient Funds: Attempting to withdraw more than available balance
• Invalid Input: Non-numeric input for amounts
• Invalid Date Format: Wrong date format in transaction filtering
• Duplicate Accounts: Attempting to create account with existing username
• Invalid PIN Format: PIN not exactly 4 digits or containing non-numeric characters

Security Features

• PIN Authentication: All accounts protected by 4-digit PIN
• Input Validation: All inputs are validated for type and format
• Session Management: Users must login before accessing banking operations
• Account Isolation: Users can only access their own account data