200 Core Java Q&A with working code, JDK 8-25 with LogicBrace

Core Java Interview Q&A — Intermediate to Professional (JDK 8 to Latest) is a 421-page PDF guide built for developers preparing for real Java interviews, not for people learning "what is a class." It covers 200 questions across 20 chapters, and every single answer includes a full explanation plus a working, commented code example — the same format as our Spring Boot Microservices guide, extended to core Java itself.

The guide moves from advanced language fundamentals (OOP internals, generics, exceptions, string/memory handling) into deep concurrency coverage (threads, java.util.concurrent, CompletableFuture, the Java Memory Model, JVM internals and garbage collection), then into functional Java (lambdas, streams), and finally into a dedicated version-history track that most interview guides skip entirely: Java 9 through 16's transition features, Java 17 LTS in full depth (sealed classes, records, pattern matching), and Java 21/25 LTS (virtual threads, structured concurrency, scoped values, sequenced collections). It closes with design patterns reimagined for modern Java, Effective-Java-style best practices, JVM performance tuning, and scenario-based questions on testing and real production debugging.

This is the guide's real differentiator: most Core Java prep material still stops at Java 8. Interviewers in 2026 increasingly ask about virtual threads, records, and pattern matching — and this guide gets those version details right, with exact JDK numbers for when each feature was previewed and standardized, so you're not caught out by "which version was that in?" follow-ups.

Every question is tagged by difficulty (Intermediate/Advanced), and every chapter ends with revision-ready key takeaways, so the guide works both for deep first-pass study and for a fast pre-interview refresher. It's fully branded and laid out as a proper reference document, with a clickable table of contents and bookmarks for quick navigation on any device.

Not sure yet? Grab the free sample chapter before you buy -https://drive.google.com/file/d/1DNE3QHCKZWcYH1msaGXdguW5HS4MqqRD/view?usp=sharing