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.
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.
