I learned by building projects I can now explain

Problem

Manage a small inventory without a database while keeping product registration, sales and available stock consistent.

Built solution

• Product registration, search, editing and deletion
• Sales with validation and stock reduction
• Category summaries and safe input handling

Demonstrated learning

I turned Java fundamentals into a complete workflow using arrays, methods, classes, encapsulation, input validation and custom exceptions.

Problem

Represent clinical and administrative processes in memory by choosing an appropriate data structure for each workflow need.

Built solution

• Patients, appointments, waiting queue and recent history
• Lists, queues, stacks, matrices and a search tree
• Sorting algorithms, reports and CSV export

Demonstrated learning

I applied lists, FIFO queues, LIFO stacks, matrices, trees, search, recursion and sorting algorithms to domain data.

Problem

Keep purchases, stock, sales and prices consistent inside a relational model whose operations affect several tables.

Built solution

• Relational model
• Stored procedures, triggers and auditing
• FIFO inventory and sales

Demonstrated learning

I designed relationships, constraints, stored procedures and triggers to protect integrity, audit changes and control FIFO inventory issues.

Problem

Build a clear and responsive academic web experience that consumed external data without presenting simulated forms as real commercial operations.

Built solution

• Menu, promotions and locations connected to a REST API
• Simulated ordering and contact without real payments or records
• Netlify build, temporary caching and fallback states

Demonstrated learning

I applied semantic HTML, modular CSS, JavaScript, API consumption, form validation, caching and publishing configuration to a multi-page experience.

Problem

Integrate distributed relational sources, a document representation and analytical processing without confusing the central demo with the complete academic scenario.

Built solution

• Catalog and reporting API with external configuration
• Distributed consolidation through postgres_fdw
• Document read model and batch KPI generation

Demonstrated learning

I worked with relational modeling, access security, distributed views, MongoDB, controlled exports and report-oriented PySpark processing.

Problem

Prevent product creation, sales calculations, state changes, alerts and export logic from being concentrated in a single class.

Built solution

• Console sale flow with customer, user, products and stock
• Subtotal, VAT, total and minimum-stock alert
• Factory Method, Builder, Command, Adapter, Facade, Observer and State

Demonstrated learning

I applied Controller, Factory Method, Builder, Command, Adapter, Facade, Observer and State to reduce coupling and assign clear responsibilities.

Problem

Expose tax ID lookups through an API without coupling the controller to the external provider while preserving request traceability.

Built solution

• Validation and lookup of 11-digit tax IDs
• HTTP integration through OpenFeign
• Query history and provider error handling

Demonstrated learning

I integrated controllers, services, OpenFeign, parameter validation, JPA persistence and consistent response and error handling.

Problem

Unify catalog, orders and inventory control so that an operation started in the interface remains consistent across both services.

Built solution

• Product CRUD, search and validation
• Order lifecycle and stock control
• H2 or PostgreSQL persistence and combined startup

Demonstrated learning

I connected React components, REST consumption, controllers, services, repositories and persistence, including stock reservation and restoration based on order state.