Overviews
Each overview page condenses an entire domain into a single scannable page: key concepts at a glance, a quick-reference API table, a suggested learning path, and the top 5 interview questions. Designed to be absorbed in under 10 minutes before an interview.
Domain Overview Pages
| Domain | What It Covers |
|---|---|
| Core Java Overview | Variables, type system, collections, streams, concurrency at a glance. |
| OOP Overview | Classes, encapsulation, inheritance, polymorphism, abstraction, records, sealed classes. |
| Java Type System Overview | Primitives, autoboxing, generics, wildcards, type erasure, and type inference. |
| Core APIs Overview | Object contract, String/StringBuilder, Math overflow-safe methods, wrappers, Optional. |
| Collections Framework Overview | List, Set, Map hierarchy, iterators, Comparable vs Comparator, immutable collections. |
| Exceptions Overview | Throwable hierarchy, checked vs. unchecked, try-with-resources, custom exceptions, best practices. |
| Functional Programming Overview | Lambdas, functional interfaces, method references, Streams, Collectors, Optional — Java 8+ essentials. |
| JVM Overview | Memory model, GC algorithms, class loading, JIT — tuning flags and diagnostics. |
| Spring Framework Overview | IoC, DI, AOP, bean lifecycle, scopes, events — key APIs and annotations. |
| Spring Boot Overview | Auto-configuration, starters, profiles, Actuator, testing slices. |
| Spring Data Overview | JPA annotations, repository methods, @Transactional propagation table, N+1 fixes, projection types. |
| Spring Security Overview | Filter chain, auth flow, JWT, OAuth2/OIDC flows, CSRF and CORS configuration. |
| Web & REST Overview | HTTP fundamentals, REST design, Spring MVC, exception handling, WebFlux, OpenAPI. |
| Multithreading Overview | Thread lifecycle, concurrency utilities, CompletableFuture cheat-table. |
| Java Design Patterns Overview | All 15 GoF patterns — intent, participants, Java/Spring examples, and top interview questions. |
| Databases Overview | SQL, indexes, ACID, HikariCP, NoSQL trade-offs, Flyway/Liquibase migration. |
| Version Control Overview | Git object model, branching strategies, rebase vs. merge, remotes, conflict resolution, hooks. |
| System Design Overview | SOLID, microservices trade-offs, caching, reliability patterns. |
| Testing Overview | JUnit 5, Mockito, Spring Boot test slices, Testcontainers, MockMvc — the full testing pyramid. |
| Projects Overview | Loan Application Evaluator — architecture, business rules, design decisions, and top interview talking points. |
How to Use These Pages
- Use full domain notes for learning — these pages are NOT substitutes for the notes.
- Use overview pages for revision — scan them the day before an interview.
- Pair each overview with the matching Interview Prep Q&A page for complete coverage.
Related Domains
- Interview Prep — per-domain Q&A pages that complement these overviews.
- Java — the Java parent domain links to all language subdomains.