
About
Java coding standards for Spring Boot and Quarkus services: naming, immutability, Optional usage, streams, exceptions, generics, CDI, reactive patterns, and project layout. Automatically applies framework-specific conventions.
name: java-coding-standards description: "Java coding standards for Spring Boot and Quarkus services: naming, immutability, Optional usage, streams, exceptions, generics, CDI, reactive patterns, and project layout. Automatically applies framework-specific conventions." origin: ECC
Java Coding Standards
Standards for readable, maintainable Java (17+) code in Spring Boot and Quarkus services.
When to Use
- Writing or reviewing Java code in Spring Boot or Quarkus projects
- Enforcing naming, immutability, or exception handling conventions
- Working with records, sealed classes, or pattern matching (Java 17+)
- Reviewing use of Optional, streams, or generics
- Structuring packages and project layout
- [QUARKUS]: Working with CDI scopes, Panache entities, or reactive pipelines
How It Works
Framework Detection
Before applying standards, determine the framework from the build file:
- Build file contains
quarkus→ apply [QUARKUS] conventions - Build file contains
spring-boot→ apply [SPRING] conventions - Neither detected → apply shared conventions only
Core Principles
- Prefer clarity over cleverness
- Immutable by default; minimize shared mutable state
- Fail fast with meaningful exceptions
- Consistent naming and package structure
- [QUARKUS]: Favor build-time over runtime processing; avoid runtime reflection where possible
Examples
The sections below show concrete Spring Boot, Quarkus, and shared Java examples for naming, immutability, dependency injection, reactive code, exceptions, project layout, logging, configuration, and tests.
Naming
// PASS: Classes/Records: PascalCase
public class MarketService {}
public record Money(BigDecimal amount, Currency currency) {}
// PASS: Methods/fields: camelCase
private final MarketRepository marketRepository;
public Market findBySlug(String slug) {}
// PASS: Constants: UPPER_SNAKE_CASE
private static final int MAX_PAGE_SIZE = 100;
// PASS: [QUARKUS] JAX-RS resources named as *Resource, not *Controller
public class MarketResource {}
// PASS: [SPRING] REST controllers named as *Controller
public class MarketController {}
Immutability
// PASS: Favor records and final fields
public record MarketDto(Long id, String name, MarketStatus status) {}
public class Market {
private final Long id;
private final String name;
// getters only, no setters
}
// PASS: [QUARKUS] Panache active-record entities use public fields (Quarkus convention)
@Entity
public class Market extends PanacheEntity {
public String name;
public MarketStatus status;
// Panache generates accessors at build time; public fields are idiomatic here
}
// PASS: [QUARKUS] Panache MongoDB entities
@MongoEntity(collection = "markets")
public class Market extends PanacheMongoEntity {
public String name;
public MarketStatus status;
}
Optional Usage
// PASS: Return Optional from find* methods
// [SPRING]
Optional<Market> market = marketRepository.findBySlug(slug);
// [QUARKUS] Panache
Optional<Market> market = Market.find("slug", slug).firstResultOptional();
// PASS: Map/flatMap instead of get()
return market
.map(MarketResponse::from)
.orElseThrow(() -> new EntityNotFoundException("Market not found"));
Streams Best Practices
// PASS: Use streams for transformations, keep pipelines short
List<String> names = markets.stream()
.map(Market::name)
.filter(Objects::nonNull)
.toList();
// FAIL: Avoid complex nested streams; prefer loops for clarity
Dependency Injection
// PASS: [SPRING] Constructor injection (preferred over @Autowired on fields)
@Service
public class MarketService {
private final MarketRepository marketRepository;
public MarketService(MarketRepository marketRepository) {
this.marketRepository = marketRepository;
}
}
// PASS: [QUARKUS] Constructor injection
@ApplicationScoped
public class MarketService {
private final MarketRepository marketRepository;
@Inject
public MarketService(MarketRepository marketRepository) {
this.marketRepository = marketRepository;
}
}
// PASS: [QUARKUS] Package-private field injection (acceptable in Quarkus — avoids proxy issues)
@ApplicationScoped
public class MarketService {
@Inject
MarketRepository marketRepository;
}
// FAIL: [SPRING] Field injection with @Autowired
@Autowired
private MarketRepository marketRepository; // use constructor injection
// FAIL: [QUARKUS] @Singleton when interception or lazy init is needed
@Singleton // non-proxyable — use @ApplicationScoped instead
public class MarketService {}
Reactive Patterns [QUARKUS]
// PASS: Return Uni/Multi from reactive endpoints
@GET
@Path("/{slug}")
public Uni<Market> findBySlug(@PathParam("slug") String slug) {
return Market.find("slug", slug)
.<Market>firstResult()
.onItem().ifNull().failWith(() -> new MarketNotFoundException(slug));
}
// PASS: Non-blocking pipeline composition
publi
Compatible Tools
Claude CodeCursor
Tags
Frontend
