ATM Management System

A comprehensive Java Swing-based ATM (Automated Teller Machine) simulation that provides banking operations and loan calculation functionality.

Application Interface

The main interface showing the PIN entry screen, numeric keypad, and loan calculation panel

Features

🔐 Security Features

• PIN Authentication: Secure 4-digit PIN verification (default: 1234)
• Account Lockout: Automatic card blocking after 3 failed PIN attempts
• Access Control: All functions disabled until successful authentication

💰 Banking Operations

• Balance Inquiry: Check current account balance
• Cash Withdrawal: Withdraw money with insufficient funds protection
• Cash Deposit: Deposit money to account
• Transaction Feedback: Real-time balance updates and confirmations

📊 Loan Management

• Loan Calculator: Calculate monthly and total payments
• Automatic Interest Rates: (£100k+) → 6%, (£20k-£99k) → 5.5%, (under £20k) → 5%
• Input Validation: Ensures all loan parameters are valid
• Receipt Generation: Detailed loan calculation receipts with timestamps

🖥️ User Interface

• Intuitive Keypad: Full numeric keypad with decimal point support (0-9, ., 00)
• Color-Coded Controls:
  • Green "Enter" button for confirmations
  • Red "Cancel" button for exits
  • Yellow "Clear" button for resets
• Dual-Panel Layout:
  • Left side: ATM operations (Balance, Withdraw, Loan, Deposit)
  • Right side: Loan calculation with receipt generation
• Clear Display: Large, readable transaction display with PIN status indicator
• Status Indicators: Real-time PIN status and system feedback
• Professional Layout: Clean, ATM-like interface design with bordered panels

System Requirements

• Java Version: Java 8 or higher
• GUI Framework: Java Swing (included in JDK)
• Memory: Minimum 256 MB RAM
• Operating System: Windows, macOS, or Linux

Usage Guide

Initial Setup

1. Launch the application
2. Enter PIN: Use the numeric keypad to enter 1234
3. Press Enter: Authenticate and unlock all features

Banking Operations

• Check Balance: Click "Balance" button to view current balance (initial: £1000.00)
• Withdraw Money:
  • Click "Withdraw" button
  • Enter amount in popup dialog
  • Confirm transaction
• Deposit Money:
  • Click "Deposit" button
  • Enter amount in popup dialog
  • Confirm transaction

Loan Calculations

1. Click "Loan" to enter loan mode
2. Fill in the required fields:
   • Number of years
   • Loan amount
3. Click "Calculate Loan" to compute payments
4. Generate Receipt for documentation
5. Reset to clear all fields

Keypad Functions

• Number buttons (1-9, 0): Input digits for PIN and amounts
• Decimal point (.): Add decimal places for monetary values
• 00: Quick double-zero input for larger amounts
• Clear (Yellow): Reset display and logout from system
• Enter (Green): Confirm PIN authentication or selections
• Cancel (Red): Exit application with confirmation dialog
• #: Reserved for future functionality

Interface Overview

The application features a professional dual-panel design:

Left Panel - ATM Operations

• Function Buttons: Balance, Withdraw, Loan, Deposit
• PIN Display Area: Shows entered PIN (masked) and status messages
• Numeric Keypad: Complete 4x4 button layout with color-coded controls

Right Panel - Loan Management

• Input Fields: Interest rate, Number of years, Loan amount
• Calculation Results: Monthly payment, Total payment (read-only)
• Action Buttons: Calculate, Reset, Receipt, Exit
• Receipt Area: Large text area for detailed loan receipts

Default Configuration

Setting	Value
Default PIN	1234
Initial Balance	£1000.00
Max PIN Attempts	3
Currency	GBP (£)

Security Notes

⚠️ Important Security Information:

• The default PIN (1234) is hardcoded for demonstration purposes
• In a production environment, PINs should be:
  • Stored securely (encrypted/hashed)
  • Retrieved from a secure database
  • Never hardcoded in source code
• Account lockout requires manual reset (contact bank simulation)

Error Handling

The system includes comprehensive error handling for:

• Invalid PIN entries with attempt tracking
• Insufficient funds protection
• Invalid input validation for all numeric fields
• Empty field validation for loan calculations
• Mathematical errors in loan computations

Technical Architecture

Core Components

• ATMS.java: Main application class with GUI and business logic
• Swing Components: Professional UI with panels and controls
• Event Handling: Comprehensive button and input event management
• Input Validation: Robust data validation for all user inputs

Key Classes & Methods

• jbtnEnterActionPerformed(): PIN authentication logic
• jbtnBalanceActionPerformed(): Balance inquiry
• jbtnWithdrawActionPerformed(): Withdrawal processing
• jbtnDepositActionPerformed(): Deposit processing
• jLoanCalActionPerformed(): Loan calculation engine
• jReceiptActionPerformed(): Receipt generation

Loan Calculation Formula

The system uses the standard loan payment formula:

Monthly Payment = P × r × (1 + r)^n / ((1 + r)^n - 1)

Where:

• P = Principal loan amount
• r = Monthly interest rate (annual rate / 12 / 100)
• n = Total number of payments (years × 12)

For zero-interest loans: Monthly Payment = Principal / Number of Months

Future Enhancements

Planned Features

• Database integration for account management
• Multiple account support
• Transaction history logging
• Network connectivity for real-time processing
• Enhanced security with encryption
• Mobile-responsive design
• Multi-language support
• Advanced loan products

Potential Improvements

• Configurable PIN requirements
• Custom currency support
• Receipt printing functionality
• Account statement generation
• Transfer between accounts
• Bill payment integration

Troubleshooting

Common Issues

Application won't start:

• Verify Java installation: java -version
• Check classpath configuration
• Ensure all files are in correct directories

PIN not accepted:

• Default PIN is 1234
• Check for numeric input only
• Verify Enter button functionality

Loan calculations incorrect:

• Verify all fields contain valid positive numbers
• Check for proper decimal formatting
• Ensure interest rate is annual percentage

Display issues:

• Check system display scaling
• Verify Swing/AWT compatibility
• Update Java to latest version

Contributing

This project is designed for educational purposes. To contribute:

1. Fork the repository
2. Create a feature branch
3. Implement improvements
4. Test thoroughly
5. Submit pull request with detailed description

License

This project is provided for educational and demonstration purposes. Please ensure compliance with local banking regulations if adapting for commercial use.

Support

For technical support or questions:

• Review the troubleshooting section
• Check Java documentation for Swing components
• Verify system requirements are met

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Disclaimer: This is a simulation for educational purposes only. Not intended for actual financial transactions or commercial banking operations.