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 chapter, you learned how to structure your code and how to save data. In the activity, you also had the opportunity to build a repository and use it to access data and save data through Room. You probably asked the question: Why do you need this repository? This chapter will seek to answer that. With the repository pattern, you will be able to retrieve data from a server and store it locally in a centralized way. The pattern is useful in situations where the same data is required in multiple places, thereby avoiding code duplication while also keeping ViewModels clean of any unnecessary extra logic.

If you look into the Settings app on your device, or the Settings feature of many apps, you will see some similarities. A list of items with toggles that can be on or off. This is achieved through SharedPreferences and PreferenceFragments. SharedPreferences is a way that allows you to store values in a file in key-value pairs. It has specialized mechanisms...