LLD Practice

Practice workspace for low-level design (LLD) and Java fundamentals. Each topic lives in its own folder so you can open a lesson and add code next to your notes.

Layout

Path	Purpose
lld-course/	LLD curriculum: SOLID, UML, design patterns, concurrency, advanced topics
java-fundamentals/	Java basics for LLD: OOP, collections, interfaces, enums, errors, packages

Empty lesson folders use .gitkeep until you add source files.

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LLD course (lld-course/)

Numbered modules; each leaf folder is one lesson.

Module	Topics
01-introduction	Introduction to LLD, software design principles
02-solid-principles	SRP, OCP, LSP, ISP, DIP
03-uml	UML, class diagrams
04-creational-patterns	Intro, singleton, factory method, builder, abstract factory, prototype
05-structural-patterns	Adapter, overview, facade, proxy, bridge, flyweight
06-behavioural-patterns	Iterator through memento (full set in repo)
07-concurrency	Threads, pools, safety, deadlocks, locks, producer–consumer (+ supplement folder for extra PC material)
10-advanced-topics	Exceptions / error handling, database design

Practice code for these lessons is not in the repo yet (folders are a scaffold aligned with typical course titles).

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Java fundamentals (java-fundamentals/)

Work through the sections below in order unless you are jumping back to review. In each table, Folder is relative to that section’s path (for example, under OOP basics, 01-classes-and-objects is java-fundamentals/01-oop-basics/01-classes-and-objects/). Lesson code and run.sh sit inside that leaf folder when present.

OOP basics (01-oop-basics/)

Folder	Topic	Done
01-classes-and-objects	Classes & objects	✓
02-constructors	Constructors	✓
03-encapsulation	Encapsulation	✓
04-inheritance	Inheritance	✓
05-polymorphism	Polymorphism	✓
06-abstraction	Abstraction (abstract, interface)	✓
07-try-it-yourself	Session 1 capstone (skeletons; tasks in each .java header)	✓

Interfaces (02-interfaces/)

Folder	Topic	Done
01-interface-usage	implements, multiple interfaces on one class	✓
02-practice	Short exercise (skeletons; tasks in each .java header)	✓

Collections (03-collections/)

Folder	Topic	Done
01-list-and-arraylist	List, ArrayList, iteration	✓
02-map-and-hashmap	Map, HashMap, LinkedHashMap, TreeMap	✓
03-set-and-hashset	Set, HashSet, LinkedHashSet, TreeSet	✓
04-module-final	Module capstone (list + map + set; tasks in each .java header)	✓

Enums (04-enums/)

Folder	Topic	Done
01-enums	Enum type, constants, fields, values, valueOf, switch	✓
02-practice	Short exercise (ChipColor / ChipPracticeApp; tasks in each .java header)	✓

Access control (05-access-control/)

Folder	Topic	Done
01-access-modifiers	private, package-private, protected, public	✓

Design thinking (06-design-thinking/)

Folder	Topic	Done
01-composition-vs-inheritance	HAS-A (composition) vs IS-A (extends)	✓
02-practice	Short exercise (Laptop + DesignPracticeApp; tasks in each .java header)	✓

Error handling (07-error-handling/)

Folder	Topic	Done
01-exception-basics	try / catch / finally, runtime exceptions	✓

Code structure (08-code-structure/)

Folder	Topic	Done
01-packages	package, folders, import, classpath	✓

Java fundamentals folders tracked in this README are covered through 08-code-structure.

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How to use

1. Pick a java-fundamentals topic until you are comfortable implementing small classes and using List / Map.
2. Work through lld-course in module order; implement examples in the matching leaf folder.
3. Keep one small runnable snippet or mini-project per folder, or introduce a shared build tool later if you outgrow single files.

Course videos (if you keep them elsewhere) are not stored in this repo; folder names align with typical lesson titles.