Java Projects for Every Skill Level
Java projects on CodeAj range from straightforward CRUD apps to multi-module enterprise systems. Whether you're a student building your first Spring Boot app or a developer who needs a reference implementation for a design pattern, we have something for you.
Spring Boot Web Applications
Our Spring Boot collection includes REST APIs with Spring Security (JWT and OAuth2), web apps with Thymeleaf templates, and microservice architectures with Spring Cloud. Each project uses Spring Data JPA for database access, Spring Validation for input checking, and proper exception handling with @ControllerAdvice. The application.yml files are organized with profiles for dev, test, and production.
Enterprise Patterns
Larger projects demonstrate patterns you'll encounter in professional Java development — repository pattern, service layer, DTO mapping with MapStruct, pagination with Spring Data, audit logging, event-driven communication, and caching with Redis. These patterns are what interviewers ask about and what real codebases use.
Android Applications
Android projects use Kotlin or Java with the latest Android SDK. They include proper MVVM architecture with ViewModel and LiveData, Room database for local storage, Retrofit for API calls, and Navigation Component for screen management. UI follows Material Design 3 guidelines.
Build and Dependency Management
All projects use Maven or Gradle with properly defined dependencies. You won't see version conflicts or missing transitive dependencies. Build files are clean and commented, so you understand what each dependency is for. Multi-module projects use parent POMs or Gradle composite builds.
