Java Interview Mastery — Core to Advanced

I have been on both sides of Java interviews for 6+ years. Most candidates memorize answers and crumble at the first follow-up question. This guide teaches you the WHY behind every concept so you can answer anything — even questions you have never seen.

What is inside:

• OOP Concepts explained the way interviewers want to hear them

• String, Immutability, equals/hashCode contract

• Collections Deep Dive — How HashMap REALLY works internally, ConcurrentHashMap, ArrayList vs LinkedList, LRU Cache implementation

• Multithreading & Concurrency — synchronized vs volatile vs Atomic, ExecutorService, CompletableFuture, Deadlock detection

• JVM Internals — Memory Model, Garbage Collection algorithms & tuning, ClassLoading

• Java 8 to 21 — Streams, Optional, Records, Sealed Classes, Virtual Threads

• Design Patterns & SOLID Principles with real examples

• Tricky output-based questions that catch even senior developers

• Cheat sheets for last-minute revision

100+ questions with detailed answers. Marked by difficulty. Written in simple language. No fluff.

This is the guide I wish I had when I started interviewing.