Book Image

How to Build Android Apps with Kotlin

By : Alex Forrester, Eran Boudjnah, Alexandru Dumbravan, Jomar Tigcal
Book Image

How to Build Android Apps with Kotlin

By: Alex Forrester, Eran Boudjnah, Alexandru Dumbravan, Jomar Tigcal

Overview of this book

Are you keen to get started building Android 11 apps, but don’t know where to start? How to Build Android Apps with Kotlin is a comprehensive guide that will help kick-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 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. Moving ahead, you'll get to grips with testing, learn how to keep your architecture clean, understand how to persist data, and gain 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 (17 chapters)
Preface
12
12. Dependency Injection with Dagger and Koin

Introduction

In the previous chapters, you learned how to write unit tests. The question is: what can you unit test? Can you unit test activities and fragments? They are pretty hard to unit test on your machine because of the way they are built. Testing would be easier if you could move the code away from activities and fragments.

Also, consider the situation where you are building an application that supports different orientations, such as landscape and portrait, and supports multiple languages. What tends to happen in these scenarios by default is that when the user rotates the screen, the activities and fragments are recreated for the new display orientation. Now, imagine that happens while your application is in the middle of processing data. You have to keep track of the data you are processing, you have to keep track of what the user was doing to interact with your screens, and you have to avoid causing a context leak.

Note

A context leak occurs when your destroyed...