02 — Learn: Basics to Advanced

Part of: docs/00-INDEX.md

Read chapters in order. Each links to runnable .java files.

1. Read one chapter (15–25 min)
2. Run the code: java pkg1core/core1HelloWorld.java
3. Experiment — change code, re-run
4. For interviews → matching 03-interview topic

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Before chapter 01

Doc	Purpose
01-orientation/01-TutorialAndHistory.md	What is Java?
01-orientation/02-LearningPath.md	Package run order

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Chapters 01–09 — Java basics

Ch	Title	Code
01	Getting Started	pkg0intro, core1HelloWorld
02	Variables & Types	core2, core3
03	Operators & Casting	core4
04	Control Flow	core5
05	Loops	core6
06	Methods	core7
07	Arrays	core8
08	Strings	core9
09	User Input	core24

Chapters 10–15 — OOP

Ch	Title	Code
10	Classes & Objects	core25
11	Constructors & Encapsulation	core26, core10
12	Inheritance & Polymorphism	core11, core12
13	Abstraction & Interfaces	core13, core14
14	Static & Enums	core27, core15
15	Records & Sealed	core16, core17

Chapters 16–21 — Core APIs

Ch	Title	Code
16	Exceptions	core18
17	Collections	core19, core28
18	Generics	core20
19	Lambdas	core21
20	Streams & Optional	core22, core23
21	Java 5→21	pkg2versions

Chapters 22–24 — CS & practice

Ch	Title	Code
22	Data Structures	pkg3datastructures
23	Algorithms	pkg4algorithms
24	LeetCode	pkg5leetcode

Chapters 25–27 — Senior

Ch	Title	Code
25	JVM & Memory	pkg6jvm
26	Concurrency	pkg7, pkg16
27	Design Patterns	pkg8patterns

Chapters 28–32 — Applied Java

Ch	Title	Code
28	I/O & NIO	pkg9io
29	Networking	pkg10networking
30	JDBC	pkg11jdbc
31	REST APIs	pkg12restapi
32	Std Libraries	pkg13libs

Chapters 33–41 — Professional & full-stack

Ch	Title	Code
33	Testing	pkg14testing
34	Modules & SPI	pkg15modules
35	Serialization	pkg20serialization
36	Performance & Build	pkg19, build/
37	Interview Prep	03-interview/
38	Metaprogramming	pkg17metaprogramming
39	Resilience Patterns	pkg18resiliencepatterns
40	Spring Boot Intro	pkg21spring
41	REST & Frontend	projects/05-notes-web

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Projects (hands-on labs)

See 07-projects/00-INDEX.md for the full ladder (gradebook → library → todo REST → Spring notes → browser UI).

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Package map (learn path)

Package	Chapters	Topics
pkg0intro	01	Hello World, setup
pkg1core	01–15	Core language & OOP
pkg2versions	21	Java 5→21 features
pkg3datastructures	22	DS implementations
pkg4algorithms	23	Sorting, searching, graphs
pkg5leetcode	24	LeetCode study plans (+ common/ helpers)
pkg6jvm	25	JVM, memory, GC
pkg7concurrency	26	Threads, executors
pkg16advconcurrency	26	JMM, advanced concurrency
pkg8patterns	27	Design patterns
pkg9io–pkg15modules	28–34	I/O, networking, JDBC, REST, libs, testing, modules
pkg17metaprogramming	38	Annotations, proxies, reflection
pkg18resiliencepatterns	39	Circuit breaker, retry, bulkhead
pkg19performance–pkg20serialization	35–36	Performance, serialization
pkg21spring	40–41	Spring Boot notes API

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Milestones

After ch.	You can…
09	Write a console program with loops, methods, classes
15	Model problems with OOP
20	Use Collections + Streams on real data
23	Implement DSA from memory
27	Explain JVM, threads, patterns
32	Build file/HTTP/DB-backed apps
37	Pass senior Java interviews
40	Build Spring Boot services with resilience patterns
41	Connect a browser UI to your Java API

Quick ref → 05-quick-ref/00-INDEX.md

Start → 01 Getting Started