Java Interview Notes — Deep & Easy Edition
21 topics of core Java through concurrency and Java 8, each explained with a simple everyday analogy first, then full technical depth, a working code example with output, an interview tip, and common interview Q&A — variables and scope, the four pillars of OOP, abstract class vs interface, key keywords (this/super/static/final), arrays/strings/number systems, exception handling, the Collections Framework, multithreading and concurrency, Java 8+ features, JVM memory management and garbage collection, serialization, design patterns and generics, annotations and reflection, inner classes, immutability, and file handling.
This is the one I'd hand to someone who understands Java syntax but freezes when asked to explain why something works. The analogy-first structure is deliberate — I've watched people recite the four pillars of OOP without being able to explain encapsulation in one plain sentence, and that's the gap this closes. JVM memory management and garbage collection is the chapter most people underprepare for, and it's also the one interviewers actually ask about most.