Kotlin For Android Development

Android development changed completely when Google made Jetpack Compose the recommended UI toolkit. The old View system, XML layouts, and findViewById are still out there — but new apps are built with Compose, and developers who learn the modern stack now are building on the foundation that will carry them through the next decade of Android engineering.

Kotlin for Android Development teaches the entire modern Android stack, layer by layer, through a single evolving project: KontactBook, the contact manager built in Book 1, reimagined as a native Android application.

WHAT YOU WILL BUILD

KontactBook for Android starts as a hardcoded list of contacts in a LazyColumn and grows into a production-quality app: animated navigation between screens, a ViewModel that survives screen rotation, form validation with real-time feedback, a custom Material 3 colour scheme with dark mode, a Room database that persists contacts across launches, a Retrofit integration that syncs with a remote API, Coil-powered photo loading, camera integration, device contact import, a complete test suite, and a Play Store listing. Fifteen chapters, fifteen real features.

WHAT YOU WILL LEARN

The first three chapters establish the Android foundation: the Activity lifecycle, the Compose mental model (composition, recomposition, and the Compose phase system), state management with remember and mutableStateOf, and state hoisting as the pattern that keeps composables testable and reusable.

Chapters 4 and 5 cover layout and navigation. You will learn the Compose layout model — how Row, Column, Box, and ConstraintLayout measure and place their children — and how to build adaptive layouts that respond correctly on phones, tablets, and foldables. Navigation with NavController introduces the back stack, typed arguments, and deep links.

Chapter 6 is the architectural pivot of the book: ViewModel, StateFlow, and collectAsStateWithLifecycle wire together into the unidirectional data flow pattern that underlies every well-structured Android app. You will understand why the ViewModel survives configuration changes, how to model UI state as a single data class, and how to handle one-shot events — Snackbars, navigation triggers — without the bugs that come from misusing StateFlow.

Chapters 7 and 8 complete the UI layer: form validation with real-time error display, Material 3 theming from seed colour to full palette using the HCT colour space algorithm, custom typography, and dynamic colour on Android 12 and later.

Chapters 9 through 13 cover data: Room for local persistence with reactive Flow of Contact lists, Retrofit and kotlinx.serialization for remote sync, Coil for efficient image loading, and the Android camera and contacts APIs for device integration.

Chapter 14 covers testing — UI tests with ComposeTestRule, ViewModel tests with TestDispatcher, and repository tests with a fake Room database. Chapter 15 walks through the full Play Store submission process.