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

Repository

Repository is a pattern that helps developers keep code for data sources separate from activities and ViewModels. It offers centralized access to data that can then be unit tested:

Figure 11.1: Diagram of repository architecture

In the preceding diagram, you can see the central role the repository plays in an application's code. Its responsibilities include:

  • Keeping all the data sources (SQLite, Network, File System) required by your activity or the application
  • Combining and transforming the data from multiple sources into a single output required at your activity level
  • Transferring data from one data source to another (saving the result of a network call to Room)
  • Refreshing expired data (if necessary)

Room, network layer, and FileManager represent the different types of data sources your repository can have. Room may be used to save large amounts of data from the network, while the filesystem can be used to store...