🏦 Console Banking System

A feature-rich console-based banking application built in Java, demonstrating object-oriented programming principles, inheritance, and role-based access control. This system provides comprehensive banking operations with separate user and administrative interfaces.

📋 Table of Contents

• Features
• Architecture
• Prerequisites
• Installation
• Usage
• Class Structure
• Security Notes
• Contributing
• License

✨ Features

User Features

• Account Management

  • User registration with age validation (18+ required)
  • Secure login with username and password authentication
  • Personal account dashboard

• Banking Operations

  • View account balance in real-time
  • Deposit funds with validation
  • Withdraw funds with insufficient balance protection
  • Comprehensive transaction history

• Security

  • Input validation for all financial transactions
  • Protection against negative amounts
  • Session-based authentication

Admin Features

• User Management

  • View all registered users
  • Search users by username
  • Remove user accounts

• System Monitoring

  • View comprehensive activity logs
  • Track all system events (logins, transactions, deletions)
  • Audit trail for compliance

🏗️ Architecture

The system follows object-oriented design principles with a clear class hierarchy:

Person (Base Class)
├── User (extends Person)
│   └── Manages user accounts, transactions, and balance
└── Admin (extends Person)
    └── System administration and monitoring

Supporting Classes:
├── ActivityLog - System-wide event tracking
├── TransactionLog - Per-user financial transaction records
└── Main - Application entry point and UI controller

Design Patterns

• Inheritance: Person base class extended by User and Admin
• Encapsulation: Data abstraction with appropriate access modifiers
• Composition: User contains ArrayList<TransactionLog>

📦 Prerequisites

• Java Development Kit (JDK): Version 8 or higher
• Operating System: Windows, macOS, or Linux
• Terminal/Command Prompt: For running the application

🚀 Installation

1. Clone the repository

   git clone https://github.com/litch07/banking-system-java.git
   cd banking-system-java

2. Compile the source files

   javac *.java

3. Verify compilation

   # Check for .class files
   ls *.class

💻 Usage

Running the Application

java Main

Main Menu Options

---- Welcome ----
1. Sign Up       - Create a new user account
2. Sign In       - Access your account
3. Admin Login   - Administrative access
4. About me      - System information
5. Exit          - Close application

User Workflow

1. Sign Up

   • Enter name and age (must be 18+)
   • Choose username and password
   • Set initial deposit amount

2. Sign In

   • Enter credentials
   • Access personal banking menu:
     • View Balance
     • Deposit funds
     • Withdraw funds
     • View transaction history
     • Log out

Admin Workflow

Default Credentials:

• Username: admin
• Password: admin

Admin Menu:

• View all registered users
• Search for specific users
• Remove user accounts
• Monitor activity logs
• Log out

📁 Class Structure

Person.java

Base class providing common attributes for users and admins.

Fields:

• String name - Person's full name
• String username - Unique identifier
• String password - Authentication credential

Methods:

• displayDetails() - Display basic information

User.java

Represents a banking customer with full transaction capabilities.

Additional Fields:

• int age - User age (minimum 18)
• double balance - Current account balance
• ArrayList<TransactionLog> transactionLogs - Personal transaction history

Methods:

• deposit(double amount) - Add funds to account
• withdraw(double amount) - Remove funds from account
• viewTransactionLogs() - Display transaction history

Admin.java

System administrator with elevated privileges.

Methods:

• authenticate(String username, String password) - Verify admin credentials
• viewAllUsers(ArrayList<User> users) - List all users
• searchUser(ArrayList<User> users, String username) - Find specific user
• deleteUser(ArrayList<User> users, String username) - Remove user
• viewActivityLogs(ArrayList<ActivityLog> activityLogs) - Monitor system activity

ActivityLog.java

Records system-wide events for auditing purposes.

Fields:

• String username - Actor
• String activityType - Event type
• double amount - Associated value (if applicable)
• LocalDateTime time - Timestamp

TransactionLog.java

Tracks individual financial transactions.

Fields:

• String username - Account owner
• String transactionType - Deposit/Withdraw
• double amount - Transaction value
• double newBalance - Balance after transaction
• LocalDateTime time - Timestamp

🔒 Security Notes

⚠️ Educational Purpose Only

This application is designed for learning and demonstration. It contains several intentional simplifications:

• In-Memory Storage: All data is lost when the application closes
• Plain Text Passwords: Credentials are not hashed or encrypted
• No Persistence: No database or file storage implementation
• Basic Validation: Limited input sanitization

For Production Use, Consider:

• Password hashing (BCrypt, Argon2)
• Database integration (MySQL, PostgreSQL)
• Exception handling for invalid inputs
• Session management and timeouts
• Multi-factor authentication
• Encryption for sensitive data
• Input sanitization against injection attacks

🤝 Contributing

Contributions are welcome! Here are some ways you can improve this project:

1. Add database persistence
2. Implement password encryption
3. Add more transaction types (transfers, bill payments)
4. Create a graphical user interface (GUI)
5. Add unit tests
6. Implement transaction limits and fraud detection

Steps to Contribute:

1. Fork the repository
2. Create a feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

📧 Contact

For questions or suggestions, please open an issue on GitHub.

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