giuseppe-trisciuoglio/developer-kit

Comprehensive developer toolkit providing reusable skills for Java/Spring Boot, TypeScript/NestJS/React/Next.js, Python, PHP, AWS CloudFormation, AI/RAG, DevOps, and more.

Quality

90%

Does it follow best practices?

Impact

Pending

No eval scenarios have been run

Securityby

Risky

Do not use without reviewing

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paths:: **/*.java

Rule: Java Best Practices

Name: giuseppe-trisciuoglio/developer-kit
Rating: 90.85333333333334 (1 reviews)
Author: giuseppe-trisciuoglio

Context

Enforce modern Java (17+) and Spring Boot best practices to produce clean, maintainable, and performant code.

Guidelines

Dependency Injection

Always use constructor-based injection, never field injection
Use @RequiredArgsConstructor (Lombok) or explicit constructors
Declare injected fields as private final
Avoid @Autowired annotation — constructor injection is implicit with a single constructor

Modern Java Features (17+)

Use Records for DTOs, value objects, and immutable data carriers
Use sealed classes and sealed interfaces for restricted type hierarchies
Use pattern matching for instanceof checks
Use text blocks for multi-line strings (SQL, JSON, templates)
Use switch expressions with arrow syntax and pattern matching
Prefer var for local variables when the type is obvious from context

Collections and Streams

Prefer List.of(), Set.of(), Map.of() for immutable collections
Use Optional for return types that may be absent — never for fields or parameters
Use Streams for data transformation pipelines, not for simple iterations
Avoid nested streams — extract to named methods for readability

Spring Boot Specific

Use @RestController with @RequestMapping at class level
Return ResponseEntity<> from controllers for explicit HTTP status control
Use @Valid for request body validation with Jakarta Validation annotations
Use @Transactional on service methods, not on repository methods
Prefer application.yml over application.properties
Use @ConfigurationProperties for type-safe configuration binding

Code Quality

Keep methods short (max ~20 lines of logic)
Favor composition over inheritance
Use meaningful names — avoid abbreviations (e.g., customer not cust)
Annotate nullable parameters/returns with @Nullable from jakarta.annotation
Use Objects.requireNonNull() for defensive null checks in constructors
Write toString(), equals(), and hashCode() only when semantically needed (Records handle this automatically)

Examples

✅ Good

@RestController
@RequestMapping("/api/orders")
@RequiredArgsConstructor
public class OrderController {

    private final OrderService orderService;

    @PostMapping
    public ResponseEntity<OrderResponse> createOrder(@Valid @RequestBody OrderRequest request) {
        var order = orderService.create(request);
        return ResponseEntity.status(HttpStatus.CREATED).body(order);
    }
}

❌ Bad

@RestController
public class OrderController {

    @Autowired
    private OrderService orderService;  // Field injection

    @PostMapping("/api/orders")
    public OrderDTO createOrder(@RequestBody Map<String, Object> request) {  // No validation, raw Map
        return orderService.create(request);
    }
}