Software Craftsmanship

Big-O, arrays, lists, stacks, queues, trees, graphs, hashing, sorting, and searching.

Naming, small functions, comments, and formatting - with before/after refactors.

Each principle with a violation, a refactored fix, and a visual metaphor.

DRY, KISS, YAGNI, Separation of Concerns, Least Astonishment, Law of Demeter, and more.

High cohesion, low coupling, composition over inheritance, program to interfaces, immutability, and DI.

Singleton, Factory Method, Abstract Factory, Builder, and Prototype.

Adapter, Decorator, Facade, Proxy, Composite, Bridge, and Flyweight.

Strategy, Observer, Command, State, Template Method, Chain of Responsibility, and more.

Naming, formatting, package layout, Javadoc, and idiomatic-Java checklists.