Backend Technologies · Java
Micronaut — Free Learning Resources
Free, printable resources for Micronaut — practice problems, quick-reference cheatsheet, and an interview prep sheet. No sign-up required.
Micronaut — Practice Worksheet
Structured exercises and problems to build hands-on Micronaut skills. Work through key concepts step by step.
Micronaut — Cheatsheet
One-page quick-reference for Micronaut — key syntax, commands, patterns, and best practices at a glance.
Micronaut — Interview Sheet
Top Micronaut interview questions with concise answers. Get ready for any technical round with this focused prep sheet.
About Micronaut
Micronaut is a JVM framework for building modular, easily testable microservice and serverless applications. Unlike Spring, Micronaut performs dependency injection and AOP at compile time using annotation processors — resulting in near-instant startup and minimal memory usage without requiring GraalVM.
MicronautCheat Sheet — What's Covered
- ✓Compile-time DI — @Singleton, @Prototype, @Inject, and bean factories
- ✓HTTP server and HTTP client with reactive support via Project Reactor / RxJava
- ✓Data access — Micronaut Data (compile-time JPA repositories)
- ✓Configuration — @ConfigurationProperties and environment-aware bindings
- ✓Testing — @MicronautTest for fast integration tests
Frequently Asked Questions — Micronaut
How is Micronaut's DI different from Spring's?
Micronaut processes @Inject annotations at compile time using APT/KAPT, generating code that wires dependencies directly — no reflection at runtime. Spring scans and resolves beans at startup using reflection. Micronaut's approach eliminates startup reflection overhead and is GraalVM-native friendly.
What is Micronaut Data?
Micronaut Data is a compile-time data access toolkit similar to Spring Data. Define a repository interface with @Repository extending CrudRepository. Micronaut Data generates the SQL at compile time — no runtime reflection or dynamic proxies. Supports JPA, JDBC, and R2DBC.
How does Micronaut handle configuration?
Annotate a class with @ConfigurationProperties('myapp') and declare typed fields. Micronaut binds application.yml values to the class at startup. @Value injects individual properties. Environment-specific config files (application-prod.yml) override defaults.
How do you test Micronaut applications?
@MicronautTest starts a real Micronaut application context for integration tests. It's fast because Micronaut's startup is sub-second. Use @MockBean to replace specific beans with mocks. The embedded server allows full HTTP testing without deploying.
When should you choose Micronaut over Spring Boot?
Choose Micronaut for memory-constrained deployments, serverless functions, or when sub-second startup is critical. Choose Spring Boot for the richest ecosystem, team familiarity, and complex enterprise integrations. Both support GraalVM native, but Micronaut requires less configuration for native builds.
Who Is This For?
Java/Kotlin/Groovy developers building microservices or serverless functions who need Spring-like DI with significantly faster startup and lower memory footprint.