Book Image

How to Build Android Apps with Kotlin - Second Edition

By : Alex Forrester, Eran Boudjnah, Alexandru Dumbravan, Jomar Tigcal
5 (1)
Book Image

How to Build Android Apps with Kotlin - Second Edition

5 (1)
By: Alex Forrester, Eran Boudjnah, Alexandru Dumbravan, Jomar Tigcal

Overview of this book

Looking to kick-start your app development journey with Android 13, but don’t know where to start? How to Build Android Apps with Kotlin is a comprehensive guide that will help jump-start your Android development practice. This book starts with the fundamentals of app development, enabling you to utilize Android Studio and Kotlin to get started with building Android projects. You'll learn how to create apps and run them on virtual devices through guided exercises. Progressing through the chapters, you'll delve into Android's RecyclerView to make the most of lists, images, and maps, and see how to fetch data from a web service. You'll also get to grips with testing, learning how to keep your architecture clean, understanding how to persist data, and gaining basic knowledge of the dependency injection pattern. Finally, you'll see how to publish your apps on the Google Play store. You'll work on realistic projects that are split up into bitesize exercises and activities, allowing you to challenge yourself in an enjoyable and attainable way. You'll build apps to create quizzes, read news articles, check weather reports, store recipes, retrieve movie information, and remind you where you parked your car. By the end of this book, you'll have the skills and confidence to build your own creative Android applications using Kotlin.
Table of Contents (24 chapters)
1
Part 1: Android Foundation
6
Part 2: Displaying Network Calls
12
Part 3: Testing and Code Structure
17
Part 4: Polishing and Publishing an App

Android components background

In many situations, you have to use onSaveInstanceState to save the current state of your activity/fragment, and then in onCreate or onRestoreInstanceState, you need to restore the state of your activity/fragment. This adds extra complexity to your code and makes it repetitive, especially if the processing code is part of your activity or fragment.

These scenarios are where ViewModel and LiveData come in. ViewModels are components built with the express goal of holding data in case of lifecycle changes. They also separate the logic from the Views, which makes them very easy to unit-test. LiveData is a component used to hold data and notify observers when changes occur while taking their lifecycle into account.

In simpler terms, the fragment only deals with the Views, ViewModel does the heavy lifting, and LiveData deals with delivering the results to the fragment, but only when the fragment is there and ready.

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