Interview Prep
This section aggregates the most important interview questions from each domain into dedicated per-domain Q&A pages. Each page organizes questions by difficulty (Beginner / Intermediate / Advanced) so you can focus revision time efficiently based on the role level you're targeting.
What You'll Find Here
| Domain | Focus Areas |
|---|---|
| Core Java Interview Q&A | Variables, operators, OOP, type system, String, Collections fundamentals. |
| OOP Interview Q&A | Classes, encapsulation, inheritance, polymorphism, abstraction, records, sealed classes. |
| Core APIs Interview Q&A | Object class contract, String/StringBuilder, Math, wrapper types, Optional patterns. |
| Exceptions Interview Q&A | Throwable hierarchy, checked vs. unchecked, try/catch/finally, custom exceptions, best practices. |
| Functional Programming Q&A | Lambdas, functional interfaces, method references, Streams, Collectors, parallel streams, Optional. |
| Multithreading Interview Q&A | synchronized, volatile, CompletableFuture, virtual threads. |
| Java Design Patterns Q&A | All 15 GoF patterns — Singleton, Proxy, Strategy, Observer, Template Method, State, and more. |
| JVM Internals Interview Q&A | GC algorithms, class loading, JIT compilation, memory areas. |
| Spring Framework Q&A | IoC, DI, AOP, bean scopes, bean lifecycle, events — proxy internals and transactional events. |
| Spring Boot Q&A | Auto-configuration, starters, Actuator, profiles, testing slices. |
| Spring Data Q&A | JPA mapping, transaction propagation, N+1 problem, projections, caching, @Transactional. |
| Spring Security Q&A | Filter chain, OAuth2 flows, JWT validation, method security, CSRF, CORS. |
| Web & REST Q&A | HTTP fundamentals, REST design, Spring MVC, exception handling, WebFlux, OpenAPI. |
| Databases Q&A | SQL fundamentals, indexes, ACID, HikariCP, NoSQL trade-offs, Flyway vs Liquibase. |
| Version Control Q&A | Git object model, branching strategies, rebase vs. merge, remotes, conflict resolution, hooks. |
| System Design Q&A | Microservices trade-offs, caching, reliability patterns, API design. |
| Testing Q&A | JUnit 5, Mockito, Spring Boot test slices, integration tests, Testcontainers, MockMvc, WebTestClient. |
| Resume-Based Q&A | Questions mapped to specific resume experiences — Struts migration, Veracode security hardening, Docker/K8s, Apache POI, and STAR behavioral questions. |
How to Use This Section
- Skim Beginner questions in each page to confirm you have no blind spots in the basics.
- Focus revision time on Intermediate questions — these are the target for 3–5 YOE roles.
- Work through Advanced questions to prepare for senior and staff engineer interviews.