REST API Interview Questions for 5 Years Experience
REST API Interview Questions for 5 Years Experience Work through these 12 questions out loud. Open any question for the full model answer, the trap to avoid, and the follow-up a panel usually asks.
How do you version REST APIs?
We use /api/v1/users for clarity. Non-breaking: add optional JSON fields. Breaking: launch v2 path, maintain v1 for 6 months with Deprecation header. Spring maps...
Explain sealed classes and their purpose in Java 17+.
sealed interface Shape permits Circle, Rectangle limits who implements Shape. Compiler verifies switch (Shape s) covers all cases — no default needed. Use for domain variants...
Explain structured concurrency and why it matters.
In a request handler, open StructuredTaskScope, fork fetchUser and fetchOrders, join both — if orders fail, user fetch cancelled automatically. Safer than manual Future...
How do Spring Boot Actuator health probes work with Kubernetes?
Enable probes, configure K8s readinessProbe on /actuator/health/readiness, liveness on /actuator/health/liveness. Custom HealthIndicator for critical deps on readiness group...
How does Micrometer Tracing replace Spring Cloud Sleuth?
Dependencies: micrometer-tracing-bridge-otel, opentelemetry-exporter-otlp. Traces propagate Authorization-safe headers across RestClient/WebClient calls. Correlate logs with...
@RestController vs @Controller?
@Controller is for traditional MVC — return "user/list" view name. @RestController adds @ResponseBody so return types become JSON/XML body — standard for REST APIs. Use...
What is ProblemDetail (RFC 7807) in Spring 6 error handling?
@ExceptionHandler(NotFoundException.class) ProblemDetail handle(NotFoundException ex) { return ProblemDetail.forStatusAndDetail(NOT_FOUND, ex.getMessage()); } — consistent 404...
springdoc-openapi vs legacy springfox — what should new projects use?
Add springdoc-openapi-starter-webmvc-ui dependency. Annotate with @Operation, @Schema on DTOs. Disable in prod via springdoc.api-docs.enabled=false or secure endpoint. Generate...
How would you design a rate-limited REST API?
API gateway or filter applies token bucket per API key — Redis stores tokens with TTL. Exceeding limit returns 429 + Retry-After. Different tiers per plan. Log rejections for...
How do you handle exceptions globally in Spring?
Create @RestControllerAdvice with @ExceptionHandler(MethodArgumentNotValidException.class) returning 400 + field map, NotFoundException → 404, generic Exception → 500 without...
What is the difference between JPA and Hibernate?
JPA is the API contract; Hibernate is the engine under Spring Boot by default. You write @Entity per JPA spec; Hibernate handles SQL generation. Spring Data JpaRepository adds...
How does Stream API parallel stream work?
parallelStream() splits work across common pool threads. Good for CPU-heavy map on large in-memory collections. Bad for small lists, IO inside stream, or ordered stateful...
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