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

Supporting Different Item Types

In the previous sections, we learned how to handle a list of items of a single type (in our case, all our items were CatUiModel). What happens if you want to support more than one type of item? A good example of this would be having group titles within our list.

Let's say that instead of getting a list of cats, we instead get a list containing happy cats and sad cats. Each of the two groups of cats is preceded by a title of the corresponding group. Instead of a list of CatUiModel instances, our list would now contain ListItem instances. ListItem might look like this:

sealed class ListItem {
    data class Group(val name: String) : ListItem()
    data class Cat(val data: CatUiModel) : ListItem()
}

Our list of items may look like this:

listOf(
    ListItem.Group("Happy Cats"),
    ListItem.Cat(
        CatUiModel...