🏗️ Java Engineering

Welcome! This repository serves as a professional portfolio for mid-to-advanced backend projects. While my Java Learning focuses on core syntax and basic algorithms, this section highlights complex systems, multi-layered architecture, and real-world engineering challenges.

🏛️ Featured Engineering Projects (With Full History)

The following projects were developed under professional mentorship. They include full commit history to demonstrate the evolution of the code, architectural decisions, and the problem-solving process.

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💹 StockMarketSystem_V0.1

A high-performance multithreaded simulation of a Stock Exchange.

• Key Focus: Advanced thread synchronization using ExecutorService, ReentrantReadWriteLock, and CountDownLatch.
• Technical Highlights:
  • Implemented thread-safe ConcurrentHashMap for independent broker portfolios.
  • Developed real-time equity calculation and Profit/Loss (P/L) reporting logic.
  • Verified memory structure and object allocation using VisualVM.
  • The system is equipped with a "circuit breaker" mechanism that automatically suspends all trading operations if the market index falls below a critical threshold or if the trading session time has expired.

🎓 UniversityCMS_V0.1

University Schedule Content Management System (CMS) — a backend system for educational process management, implemented in Java using PostgreSQL and multi-layered architecture.

A comprehensive educational management system built with scalability in mind.

• Key Focus: Layered Architecture (DAO, Service, Controller) and robust data persistence.
• Technical Highlights:
  • Designed complex PostgreSQL database schemas with multiple relationships.
  • Managed database versions using Flyway migrations.
  • Ensured code reliability with comprehensive JUnit 5 and Mockito testing.

🏫 SchoolManagementSystem_V0.1

A console-based School Management System built with Spring Boot, focused on modern backend practices and automated database management.

• Key Focus: Transitioning from Core Java to the Spring ecosystem, implementing automated database evolution, and adopting containerized testing.
• Technical Highlights:
  • Spring Data JPA & Hibernate: Leveraged for efficient Object-Relational Mapping (ORM) and simplified data persistence layers.
  • Flyway Migrations: Implemented automated database schema versioning to ensure consistent environments across development and testing.
  • Testcontainers: Developed robust integration tests by spinning up real PostgreSQL instances in containers during the build process.
  • Architecture: Followed a service-oriented approach to separate business logic from data access and CLI interaction.

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🛠️ Practical Skills & Tools Demonstrated

• Frameworks & Core Java:
  • Spring Boot: Building production-ready applications with dependency injection and auto-configuration.
  • Concurrency: Managing thread lifecycles with ExecutorService, ensuring synchronization via ReentrantReadWriteLock, and using CountDownLatch for thread coordination.
• Data Management & Persistence:
  • Spring Data JPA & Hibernate: Implementing ORM patterns to map Java objects to relational tables efficiently.
  • SQL & PostgreSQL: Designing complex schemas, managing relationships, and ensuring ACID compliance.
  • Database Migrations: Using Flyway for version-controlled schema evolution.
• Software Architecture:
  • Multi-tier (Layered) Architecture: Separating concerns into Controller, Service, and DAO/Repository layers.
  • Clean Code: Refactoring based on professional mentorship to ensure maintainability and readability.
• Testing & Quality Assurance:
  • Integration Testing: Using Testcontainers to run tests against real Dockerized PostgreSQL instances.
  • Unit Testing: Verifying business logic with JUnit 5 and mocking dependencies with Mockito.
• Monitoring & Tooling:
  • Performance Profiling: Monitoring heap memory, object allocation, and thread states using VisualVM.
  • Build Tools: Managing dependencies and project lifecycles with Maven.

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