Book Image

Android Studio 3.5 Development Essentials - Kotlin Edition

By : Neil Smyth
Book Image

Android Studio 3.5 Development Essentials - Kotlin Edition

By: Neil Smyth

Overview of this book

Popularity of Kotlin as an Android-compatible language keeps growing every day. This book will help you to build your own Android applications using Kotlin. Android Studio 3.5 Development Essentials Kotlin Edition first teaches you to install Android development and test environment on different operating systems. Next, you will create an Android app and a virtual device in Android studio, and install an Android application on emulators. You will test apps on physical android devices, then study Android Studio code editor, Android architecture, and the anatomy of an Android app. The focus then shifts to Kotlin language. You’ll get an overview of Kotlin language and practice converting code from Java to Kotlin. You’ll also explore Kotlin data types, operators, expressions, loops, functions, and the basics of OOP concept in Kotlin. This book will then cover Android Jetpack and how to create an example app project using ViewModel component, as well as advanced topics such as views and widgets implementation, multi-window support integration, and biometric authentication. Finally, you will learn to upload your app to the Google Play Console and handle the build process with Gradle. By the end of this book, you will have gained enough knowledge to develop powerful Android applications using Kotlin.
Table of Contents (93 chapters)
93
Index

63.4 The Anatomy of a Service

A service must, as has already been mentioned, be created as a subclass of the Android Service class (more specifically android.app.Service) or a sub-class thereof (such as android.app.IntentService). As part of the subclassing procedure, one or more of the following superclass callback methods must be overridden, depending on the exact nature of the service being created:

onStartCommand() – This is the method that is called when the service is started by another component via a call to the startService() method. This method does not need to be implemented for bound services.

onBind() – Called when a component binds to the service via a call to the bindService() method. When implementing a bound service, this method must return an IBinder object facilitating communication with the client. In the case of started services, this method must be implemented to return a NULL value.

onCreate() – Intended...