Book Image

How to Build Android Apps with Kotlin - Second Edition

By : Alex Forrester, Eran Boudjnah, Alexandru Dumbravan, Jomar Tigcal
5 (1)
Book Image

How to Build Android Apps with Kotlin - Second Edition

5 (1)
By: Alex Forrester, Eran Boudjnah, Alexandru Dumbravan, Jomar Tigcal

Overview of this book

Looking to kick-start your app development journey with Android 13, but don’t know where to start? How to Build Android Apps with Kotlin is a comprehensive guide that will help jump-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 with 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. You'll also get to grips with testing, learning how to keep your architecture clean, understanding how to persist data, and gaining 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 (24 chapters)
1
Part 1: Android Foundation
6
Part 2: Displaying Network Calls
12
Part 3: Testing and Code Structure
17
Part 4: Polishing and Publishing an App

Responding to clicks in RecyclerView

What if we want to let our users select an item from a presented list? To achieve that, we need to communicate clicks back to our app.

The first step in implementing click interaction is to capture clicks on items at the ViewHolder level. To maintain separation between our view holder and the adapter, we define a nested OnClickListener interface in our view holder. We choose to define the interface within the view holder because that and the listener are tightly coupled.

The interface will, in our case, have only one function. The purpose of this function is to inform the owner of the view holder about the clicks. The owner of a view holder is usually a Fragment or an Activity. Since we know that a view holder can be reused, we know that it can be challenging to define it at construction time in a way that would tell us which item was clicked (since that item will change over time with reuse).

We work around that by passing the currently...