Java-Based Simple Banking Transaction Simulator

A comprehensive banking transaction simulation platform built with core Java, designed to demonstrate real-world banking operations including deposits, withdrawals, transfers, and automated alerts.

📋 Project Overview

This project simulates a basic banking system that handles account management, transaction processing, and automated notifications. It leverages core Java features including exception handling, collections, and JDBC for data persistence, providing a practical understanding of banking operations without complex financial libraries.

✨ Key Features

• Account Management: Create and manage multiple bank accounts with balance tracking
• Transaction Processing: Handle deposits, withdrawals, and inter-account transfers
• Error Handling: Robust validation for overdrafts and invalid operations
• Transaction Logging: JDBC-based persistence for all transactions
• Automated Alerts: Email notifications for low balance thresholds
• Report Generation: Export transaction history and account summaries to text files
• Real-time Monitoring: Balance threshold tracking with configurable alerts

🏗️ System Architecture

Core Modules

1. Account Management Engine

• Account creation and deletion
• Balance inquiry and updates
• In-memory storage using Java Collections (HashMap, ArrayList)
• Account validation and uniqueness checks

2. Transaction Processing System

• Deposit operations with validation
• Withdrawal with overdraft protection
• Inter-account transfers
• Transaction rollback on failures
• Exception handling for invalid operations

3. Reporting and Text File Integration Hub

• Transaction history reports
• Account summary generation
• CSV/Text file export functionality
• Email API integration for notifications
• Scheduled report generation

4. Balance Alert Tracker

• Configurable balance thresholds
• Real-time account monitoring
• Automated email alerts
• Alert history logging

🛠️ Technology Stack

• Language: Java (JDK 8 or higher)
• Database: JDBC-compatible database (MySQL/PostgreSQL/H2)
• Storage: Collections Framework for in-memory data
• File I/O: Text file handling for reports
• Email: JavaMail API for notifications
• Build Tool: Maven/Gradle (optional)

📦 Prerequisites

• JDK 8 or higher installed
• JDBC-compatible database (MySQL/PostgreSQL recommended)
• Email SMTP credentials (for alert functionality)
• IDE (Eclipse/IntelliJ IDEA/VS Code recommended)

🚀 Getting Started

Installation

1. Clone the repository

git clone https://github.com/yourusername/banking-simulator.git
cd banking-simulator

2. Configure Database

CREATE DATABASE banking_simulator;
CREATE TABLE accounts (
    account_id VARCHAR(20) PRIMARY KEY,
    holder_name VARCHAR(100),
    balance DECIMAL(15,2),
    created_at TIMESTAMP
);
CREATE TABLE transactions (
    transaction_id INT AUTO_INCREMENT PRIMARY KEY,
    account_id VARCHAR(20),
    transaction_type VARCHAR(20),
    amount DECIMAL(15,2),
    timestamp TIMESTAMP,
    description VARCHAR(255)
);

3. Update Configuration

Edit config.properties:

db.url=jdbc:mysql://localhost:3306/banking_simulator
db.username=your_username
db.password=your_password
email.smtp.host=smtp.gmail.com
email.smtp.port=587
email.username=your_email@gmail.com
email.password=your_app_password
alert.threshold=1000.00

4. Compile and Run

javac -d bin src/**/*.java
java -cp bin com.banking.Main

📖 Usage Examples

Creating an Account

AccountManager accountManager = new AccountManager();
Account account = accountManager.createAccount("ACC001", "John Doe", 5000.00);

Processing Transactions

TransactionProcessor processor = new TransactionProcessor();
processor.deposit("ACC001", 1000.00);
processor.withdraw("ACC001", 500.00);
processor.transfer("ACC001", "ACC002", 250.00);

Generating Reports

ReportGenerator reportGen = new ReportGenerator();
reportGen.generateTransactionReport("ACC001", "reports/transactions.txt");
reportGen.generateAccountSummary("reports/summary.txt");

Setting Up Alerts

BalanceAlertTracker alertTracker = new BalanceAlertTracker();
alertTracker.setThreshold("ACC001", 1000.00);
alertTracker.startMonitoring();

📁 Project Structure

banking-simulator/
├── src/
│   ├── com/banking/
│   │   ├── account/
│   │   │   ├── Account.java
│   │   │   ├── AccountManager.java
│   │   │   └── AccountValidator.java
│   │   ├── transaction/
│   │   │   ├── Transaction.java
│   │   │   ├── TransactionProcessor.java
│   │   │   └── TransactionType.java
│   │   ├── reporting/
│   │   │   ├── ReportGenerator.java
│   │   │   └── FileExporter.java
│   │   ├── alert/
│   │   │   ├── BalanceAlertTracker.java
│   │   │   └── EmailNotifier.java
│   │   ├── database/
│   │   │   └── DatabaseManager.java
│   │   ├── exception/
│   │   │   ├── InsufficientFundsException.java
│   │   │   ├── InvalidAccountException.java
│   │   │   └── TransactionFailedException.java
│   │   └── Main.java
├── reports/
├── logs/
├── config.properties
└── README.md

🧪 Testing

Run comprehensive tests covering:

• Account creation and validation
• Transaction processing scenarios
• Exception handling for edge cases
• Alert triggering conditions
• Report generation accuracy

java -cp bin:junit.jar org.junit.runner.JUnitCore com.banking.tests.TestSuite

🗓️ Development Milestones

• ✅ Milestone 1 (Weeks 1-2): Environment setup and initial training
• ✅ Milestone 2 (Weeks 3-4): Account Management Engine
• ✅ Milestone 3 (Weeks 5-6): Transaction Processing & Reporting Hub
• ✅ Milestone 4 (Weeks 7-8): Balance Alert Tracker & Deployment

🔍 Error Handling

The system handles various exception scenarios:

• InsufficientFundsException: Overdraft attempts
• InvalidAccountException: Non-existent accounts
• TransactionFailedException: Database or processing errors
• InvalidAmountException: Negative or zero amounts

📊 Sample Output

Transaction Report:

=====================================
    TRANSACTION HISTORY REPORT
=====================================
Account: ACC001 | Holder: John Doe
Current Balance: $4,750.00

Date/Time            | Type      | Amount    | Description
------------------------------------------------------------------
2025-11-14 10:30:00 | DEPOSIT   | $1,000.00 | Initial deposit
2025-11-14 11:15:00 | WITHDRAW  |   $500.00 | ATM withdrawal
2025-11-14 14:45:00 | TRANSFER  |   $250.00 | Transfer to ACC002

🤝 Contributing

Contributions are welcome! Please follow these steps:

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

📄 License

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

👥 Authors

• Your Name - selvaragavan s