Java in Three Months

The parts

1. Part I · The JVM & How Java Runs Source to running code — compile once, run anywhere — and the machine underneath: bytecode, the class loader, the JIT, and the memory it all lives in.
2. Part II · Types, Objects & Generics The object model in full — classes, inheritance & the contracts that make objects behave — and generics : the type system that keeps it all honest, erasure and all.
3. Part III · The Modern Language Java 14→21 changed how you write Java — records, sealed types & pattern matching turn switch into algebra and data classes into one line. Data-oriented Java.
4. Part IV · Functional Java & Streams Functions as values — lambdas, method references & the Stream API — turn loops into declarative pipelines: map, filter, reduce, collect, and know when to go parallel.
5. Part V · Collections & Data Structures The everyday workhorses — List, Set, Map, Deque — their implementations, their Big-O trade-offs, and the judgment to reach for the right one every time.
6. Part VI · Concurrency The hardest part of Java, made mechanical — the memory model, locks & atomics , executors & futures, the concurrent collections, and Java 21's game-changer: virtual threads.
7. Part VII · Memory, GC & Performance Where the bytes live and how they're reclaimed — the heap, the garbage collectors , references & leaks — and how to measure performance honestly instead of guessing.
8. Part VIII · Stdlib, Build & the Capstone Shipping real Java — files, time, the HTTP client, Maven & JUnit — then a typed, tested, packaged 🛠 capstone , a master cheat sheet, and the canon to read next.