Interview questions for senior engineers and tech leads with eight or more years of experience: expert-level Java, JVM internals and performance, concurrency, modern Java, Spring and Spring Cloud, microservices architecture, databases at scale, Kafka and event streaming, cloud and DevOps, security, AI/LLM integration, system design scenarios and leadership questions. Starts with a rapid revision of the earlier tiers.
Rapid revision of every 5–8 year question, with one-line answers and links to the full answers.
Tricky output and language-edge questions, exceptions and keywords, reflection, proxies, cloning, final and immutability, and a fast pass over the classic Java questions with senior-level answers.
Class loading and bytecode, JIT, garbage collectors from Serial to ZGC, JVM flags and GC logs, memory leaks, profiling, modules and startup optimisation.
Collections internals and complexity, concurrent collections, executors and ForkJoin, locks and atomics, memory visibility, deadlock and starvation, CompletableFuture and virtual threads.
Lambdas, functional interfaces, streams and collectors, Optional, default methods, records, sealed types, pattern matching, virtual threads and other Java 9–21 features.
Pattern trade-offs at senior level, combining patterns, SOLID, DRY/KISS/YAGNI, anti-patterns and clean-code practices.
IoC and DI internals, AOP, bean lifecycle and scopes, configuration, auto-configuration and starters, Spring MVC, WebFlux, Spring Security, Spring Cloud and production Spring Boot scenarios.
Entity mapping, JPQL and native queries, caching levels, fetching and N+1, transactions and locking, indexing and query tuning, sharding, replication and data engineering questions.
Spring Boot testing slices, JUnit 5, Mockito, Testcontainers and contract testing, REST design, status codes, OpenAPI, validation and API versioning.
Maven and Gradle at scale, CI/CD, Git strategies, Docker and Kubernetes, cloud deployment, observability and production operations.
Kafka internals, delivery semantics, Kafka Streams, RabbitMQ and JMS, retries and dead-letter queues, and integration patterns.
Monolith vs microservices, resilience and observability, event-driven architecture and CQRS, sharding, multi-tenancy, and architecture decision-making.
Real-world design questions: booking and pricing systems, rate limiters, schedulers, notification and logging platforms, and project deep-dives.
Zero trust, OAuth2 and OIDC in depth, token design and revocation, secrets, encryption and secure backend design.
Integrating LLMs into Java backends: RAG, embeddings and vector stores, Spring AI, prompt and cost control, safety and evaluation.
The coding round for senior engineers: arrays, strings, recursion, linked lists, stacks, trees, graphs, DP, heaps, bit tricks, concurrency coding and low-level design problems.
Leadership style, mentoring and code reviews, Agile ceremonies, stakeholder communication, architecture decisions, conflict resolution and career questions.
