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

Adding Items Interactively

We have just learned how to remove items interactively. What about adding new items? Let's look into it.

Similar to the way we implemented the removal of items, we start by adding a function to our adapter:

fun addItem(position: Int, item: ListItemUiModel) {
    listData.add(position, item)
    notifyItemInserted(position)
}

You will notice that the implementation is very similar to the removeItem(Int) function we implemented earlier. This time, we also receive an item to add and a position to add it. We then add it to our listData list and notify RecyclerView that we added an item in the requested position.

To trigger a call to addItem(Int, ListItemUiModel), we could add a button to our main activity layout. This button could be as follows:

<Button
    android:id="@+id/main_add_item_button"
    android:layout_width="match_parent"
 ...