Java Backend Interview Prep
Production-grade Java preparation: Collections, OOP, Concurrency, PostgreSQL, and Spring deep-dives, plus Data Structures & Algorithms, Low-Level Design, and High-Level Design — with the JVM module slotting into the same scaffold.
Java Collections Framework
Lists, Sets, Maps, Queues, the equals/hashCode contract, concurrent collections, and the modern Sequenced Collections API. The single most-asked area in any Java interview.
Object-Oriented Programming
The four pillars, equals/hashCode, immutability, SOLID, GoF design patterns, and modern Java 25 OOP (records, sealed classes, pattern matching). About 30% of any senior Java interview.
Concurrency & Multithreading
Threads, the Java Memory Model, locks, atomics, executors, CompletableFuture, synchronizers, deadlock, and virtual threads (Loom) — the #1 senior Java filter, from middle to senior interview depth.
PostgreSQL
Relational database internals, query optimization, indexing, transactions, and operational concerns for backend interviews.
Spring Framework & Spring Boot
Spring Core, Boot, Data, Security, and internals — from middle to senior interview depth.
Data Structures & Algorithms
Language-agnostic algorithmic foundations with Java examples and Java Collections mapping. Big-O, classic data structures, algorithm paradigms, and interview pattern recognition.
Low-Level Design (LLD / OOD)
Object-oriented system design at the class level. Machine-coding round preparation: classic problems with full solutions, class diagrams, design-pattern application, and trade-off discussion.
High-Level Design (HLD / Distributed Systems)
Distributed systems and large-scale architecture interview preparation. Fundamentals (CAP, consistency, replication), building blocks (caches, queues, databases), and full system designs across FAANG, EU, and regional interview styles.