📊 Transaction Processing & Reporting System (Java)

Overview

The Transaction Processing & Reporting System is a Java-based backend application that reads financial transaction data from a CSV file, validates inputs, applies business rules, and generates a formatted account summary report.

This project demonstrates clean architecture principles, strong domain modeling, and enterprise-style Java practices commonly used in production backend systems.

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Key Features

• Reads structured transaction data from an external CSV file
• Validates transactions to prevent invalid or unsafe data
• Uses enums to enforce type safety and eliminate invalid states
• Applies business logic to calculate deposits, withdrawals, and balances
• Produces a clean, formatted account summary report
• Organized using layered architecture for maintainability

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Technologies & Concepts

• Java
• Enums for domain modeling
• File I/O (NIO)
• Exception handling
• Input validation
• Separation of concerns
• Clean architecture (model / service / util layers)

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Application Output

Account Summary Report

This output confirms:

• Correct transaction processing
• Accurate financial calculations
• Clean, readable reporting format

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Core Implementation Highlights

Transaction Processing Logic

The processor applies business rules using a type-safe enum and a switch statement to:

• Accumulate total deposits
• Accumulate total withdrawals
• Maintain a running account balance

This approach prevents invalid transaction types and improves long-term maintainability.

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Transaction Parsing & Validation

The parser:

• Converts raw CSV input into strongly typed domain objects
• Normalizes and validates transaction types using enums
• Ensures invalid data fails fast before entering the system

Validation is handled separately to keep responsibilities clearly defined.

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Project Structure

src/ ├── model/ // Domain models and enums ├── service/ // Parsing, validation, and processing logic ├── util/ // File utilities data/ └── transactions.csv

yaml Copy code

This structure mirrors real-world backend applications and supports scalability and testability.

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How It Works

1. The application reads transaction records from transactions.csv
2. Each line is parsed and validated
3. Valid transactions are processed using business rules
4. A final account summary report is generated and displayed

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Error Handling

• Invalid CSV formats throw clear exceptions
• Unsupported transaction types are rejected at parse time
• Invalid transaction amounts are blocked during validation
• File read failures surface meaningful runtime errors

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Future Enhancements

• Convert transaction dates to LocalDate
• Add insufficient-funds protection for withdrawals
• Add unit tests using JUnit
• Export reports to CSV or JSON
• Extend transaction types (e.g., TRANSFER)

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Why This Project Matters

This project demonstrates practical backend engineering skills, including:

• Defensive programming
• Domain-driven design concepts
• Clean code organization
• Enterprise-ready Java practices

It reflects the type of logic and structure used in real-world financial systems.

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How to Run

1. Clone the repository
2. Ensure transactions.csv exists in the data directory
3. Run Main.java
4. View the generated account summary in the console

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👤 Author

Ambrogio Bailey
Aspiring Backend / Software Developer
LinkedIn: https://www.linkedin.com/in/ambrogio-bailey-b67529373/