Backend

• Google Guava in Examples

  A tour of Google Guava through Kotlin examples: Multimap, BiMap, Table, caching, string utilities, hashing, IO helpers and concurrency.

• gRPC — How it works

  How gRPC works on top of HTTP/2 and Protocol Buffers, where it beats REST for internal services, and how to build a Kotlin server and client.

• Introduction to Ktor and Exposed

  Building a Kotlin server with Ktor: Exposed and JDBI for the database, Koin for dependency injection, Mockk and Testcontainers tests, Flyway migrations.

• Introduction to Project Loom

  Project Loom virtual threads in Java: how the JVM schedules them on carrier threads, how they differ from Kotlin Coroutines, and enabling them in Spring.

• Java / Kotlin Core — Multithreading

  Java and Kotlin concurrency explained: volatile, synchronized, ReentrantLock, coroutines and Channels, RxJava operators and backpressure strategies.

• Java / Kotlin Core — Theoretical Questions

  Big-O costs of collection operations, design patterns, SOLID, inheritance versus composition and higher-order functions in Java and Kotlin.

• Java Core — Basic Questions

  Java Core interview answers: data types, collections and HashMap, generics, reflection, JVM memory layout and how the garbage collector works.

• Java Spring — Cloud

  Cloud services for Java across AWS, Google Cloud and Azure: side-by-side equivalents, cost optimization, serverless, Git LFS and submodules.

• Java Spring — Concepts

  Core backend concepts behind Spring: Saga and Rollback, SOLID, Clean Architecture, REST vs RPC vs GraphQL, IoC and DI, Spring MVC and Project Reactor.

• Java Spring — Data Storage

  Data storage in Spring: ACID and isolation levels, @Transactional, JPA vs JDBC, Spring Data repositories, Redis caching, Flyway and indexes.

• Java Spring — List of Questions

  A navigable index of Java developer interview questions: Java Core, Kotlin, concurrency, Spring annotations and components, microservices, and SQL.

• Java Spring — Microservices

  Microservice communication in Spring: REST and WebClient, Kafka and RabbitMQ, Docker and Kubernetes, Eureka, Cloud Gateway, and request tracing.

• Java Spring — Spring Annotations

  A reference to Spring annotations with Kotlin examples: @Component, @Bean, @Transactional, request mapping, JPA, and how @Component differs from @Bean.

• Java Spring — Spring Components

  Configuring application.properties, WebSocket, GraphQL, OAuth 2.0, Spring Security, Actuator, WebFlux and Batch with real code and config examples.

• Kotlin 2.0 — Key Syntax Changes

  What changed in Kotlin 2.0 syntax: context receivers, value classes, sealed interfaces, destructuring in for loops and pattern matching in when.

• Kotlin Core — Basic Questions

  How coroutines and suspend actually work, when to use launch instead of async, plus scope functions, delegates, extensions and companion objects.

• Kubernetes — How it works

  How Kubernetes works: control plane architecture, namespaces, load balancing, everyday kubectl commands, the Dashboard and Prometheus monitoring.

• Microservices and Web Application Security

  Auth microservices, API Gateway, mTLS and certificates: how to store passwords safely, stop brute-force attacks and choose encryption algorithms.

• Mock Server Responses in Android Development using Interceptor

  Mocking server responses in Android with a custom OkHttp Interceptor: a MockResponse model, a URL-keyed map, and wiring it into OkHttpClient.

• Relational SQL databases

  SQL syntax, views and indexes, JOIN and CTE queries, pessimistic and optimistic locking, and reading query plans in PostgreSQL, MySQL and Oracle.

• Setup custom launch options for IntelliJ IDEA / Android Studio

  What each flag in Edit Custom VM Options actually does: heap sizes, Garbage Collector choice, code cache, and memory tuning for Android Studio.

• Small manual on MapStruct

  Practical MapStruct recipes for Kotlin: mapping mismatched field names, @Named methods, reusing mapping logic, and avoiding common compile-time errors.