Kotlin · Easy

Lesson 1 · On the house

Classes and properties

class, val/var properties, methods, instances.

Lesson 2

Constructors

Primary constructor, init blocks, secondary constructors.

Lesson 3

Inheritance

open, override, super; final by default.

Lesson 4

Interfaces

interface, implement, default methods.

Lesson 5

Visibility and objects

private/internal/public; object and companion object.

Lesson 6

Extension functions

fun Type.name, receivers; no inheritance required.

Lesson 7

Lambdas and higher-order

(Int) -> Int, trailing lambda, filter/map.

Lesson 8

Scope functions

let, run, apply, also, with — return and receiver.

Lesson 9

Sealed classes

sealed hierarchy, exhaustive when.

Lesson 10

Easy capstone

Class + interface + lambda + when in one small program.