Drills

What is the difference between @Valid and @Validated in Spring MVC?

Separates Jakarta cascaded validation, Spring validation groups, and modern MVC method validation without relying on outdated controller advice.

Comparison questionMedium~10 min

What is the difference between WSGI and ASGI for a Python web application?

Distinguishes the synchronous WSGI request contract from ASGI's asynchronous, multi-event application contract.

DjangoPython

What is the lifecycle of a Spring bean?

Walks from instantiation and dependency injection through post-processing, initialization callbacks, use, and supported destruction behavior.

Concept questionEasy~5 min

What JVM memory areas matter to a Java backend service?

Explains heap, per-thread stacks, Metaspace, code cache, and native memory through the failures and evidence they produce.

Java

What makes a unit test valuable?

Focuses unit tests on stable behavior, meaningful boundaries, deterministic outcomes, and useful failure messages.

.NETC#xUnit

Concept questionEasy~6 min

What .NET Aspire is and what it does not replace

Explains Aspire as a code-first application model and developer experience without confusing it with a production runtime or architecture style.

.NET.NET Aspire

Architecture scenarioHard~10 min

What observability baseline would you expect for a production Spring Boot API?

Combines Spring Boot signals into an operator-focused baseline for service health, dependencies, capacity, releases, and actionable alerts.

Architecture scenarioHard~15 min

What should a DRF partial update guarantee beyond accepting PATCH?

Defines omission, nullability, field ownership, invariants, concurrency, and effects for DRF partial updates.

DjangoDjango REST FrameworkPython

Architecture scenarioHard~15 min

What would you verify before deploying a Django application to production?

Turns Django's production settings, server, storage, security, and operational dependencies into a repeatable release check.

DjangoPython

Concept questionHard~10 min

When are discriminated unions useful in a FastAPI request model?

Uses an explicit discriminator to model genuine request variants with predictable validation and OpenAPI output.

FastAPIPydanticPython

Comparison questionMedium~10 min

When are FastAPI BackgroundTasks appropriate, and when do you need a real task queue?

Chooses between small in-process follow-up work and durable, independently operated background execution.

FastAPIPython

Concept questionMedium~10 min

When are Java streams clearer than loops, and when are they not?

Chooses streams or loops by transformation shape, control flow, side effects, debuggability, and measured performance.

Java

When does a Django QuerySet execute, and what does it cache?

Explains lazy query construction, evaluation triggers, result caching, and repeated-query surprises.

DjangoPython

When does Spring roll back a @Transactional method?

Explains default rollback behavior, checked exceptions, rollback rules, swallowed failures, and commit-time exceptions.

When do sealed classes or interfaces improve a Java model?

Uses sealed types for deliberately closed variants and connects them to exhaustive reasoning, evolution, and open extension boundaries.

Java

When do you choose Spring MVC versus Spring WebFlux?

Chooses between blocking Servlet execution and end-to-end non-blocking reactive execution based on dependencies, concurrency, and team cost.

When do you return ResponseEntity instead of a body directly?

Uses direct bodies for fixed successful contracts and ResponseEntity when status or headers vary by outcome.

When do you use a fetch join, entity graph, or batch fetching in Hibernate?

Chooses among explicit joins, reusable fetch graphs, and bounded secondary selects based on query shape and cardinality.

When do you use a Servlet filter, HandlerInterceptor, or ControllerAdvice?

Places protocol-wide work in filters, handler-aware MVC work in interceptors, and controller exception or body concerns in advice.

When do you use component scanning versus explicit @Bean configuration?

Chooses stereotype scanning for owned application components and explicit factory methods for third-party types, construction policy, and visible composition.

When do you use @ConfigurationProperties instead of @Value?

Uses typed grouped binding and validation for application configuration while reserving @Value for small isolated expressions.

When do you use constructor, field, or setter injection in Spring?

Prefers constructor injection for required dependencies while explaining the limited roles and costs of setter and field injection.

When do you use JPQL, native SQL, Criteria API, or Spring Data specifications?

Chooses a query representation from static versus dynamic shape, portability, database features, readability, and performance evidence.