Field Injection (ARCH4200)

Key java.quality.field-injection · Severity warning · Category quality

Annotation-based field injection hides dependencies, prevents final, and makes passing dependencies in unit tests harder. Use constructor injection.

Incorrect

@Service
class OrderService {
    @Autowired
    private PaymentGateway gateway;
}

Correct

@Service
class OrderService {
    private final PaymentGateway gateway;
    OrderService(PaymentGateway gateway) { this.gateway = gateway; }
}

Fix

Remove the field annotation and inject the dependency as a final constructor parameter.