Car Registry — Java

Java Swing desktop application for registering people and their cars, backed by MySQL. It was built during the Java classes of the Information Technology technical course at Senac Tech (2022–2023).

Origin

The project was developed in class on top of the base provided by the instructor (which is why the original classes are tagged @author jbferraz). It demonstrates the concepts covered in the course:

• Object-oriented programming with Pessoa (person) and Carro (car) models
• Layered architecture: view (Swing) → services → DAO → MySQL
• DAO and Factory patterns
• JDBC with PreparedStatement
• Validation of CPF (Brazilian taxpayer ID check digits), license plates and car years

2026 review

Now a Software Engineering undergraduate, I revisited the project:

Before	After
Database connections opened and never closed	try-with-resources in every DAO
Listing cars ran an extra query per car to fetch its owner (N+1)	A single query with a JOIN
NetBeans (Ant) build, with the MySQL driver committed as a .jar	Maven, with the driver as a dependency and an executable .jar
Database user and password hardcoded	Environment variables (DB_URL, DB_USER, DB_PASSWORD)
No easy way to start the database	MySQL via Docker Compose, initialized from the SQL script
Compiled files and local settings committed	Removed and ignored in .gitignore

Each change is in a separate commit.

Running

Requires Java 21+, Maven and Docker.

cd cadastro-carros
docker compose up -d
mvn package

Then, using the Compose database password:

DB_PASSWORD=root java -jar target/cadastro-carros-1.0.0.jar

In PowerShell, set the variable first with $env:DB_PASSWORD="root". The project also opens in NetBeans as a Maven project, including the visual form editor (.form files).

Structure

Path	Contents
view/	Swing screens (main, people and cars)
controller/	In-memory lists from the earlier console version (before the database)
servicos/	Business logic between screens and DAOs
dao/	Database access with JDBC
model/	Pessoa and Carro classes
util/	CPF, license plate and year validators
database/carro.sql	Database and table creation

The packages live in cadastro-carros/src/main/java/. The code itself (class names, UI and messages) is in Portuguese.