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

38.7 Android Lifecycles

The duration from when an Android component is created to the point that it is destroyed is referred to as the lifecycle. During this lifecycle, the component will change between different lifecycle states, usually under the control of the operating system and in response to user actions. An activity, for example, will begin in the initialized state before transitioning to the created state. Once the activity is running it will switch to the started state from which it will cycle through various states including created, started, resumed and destroyed.

Many Android Framework classes and components allow other objects to access their current state. Lifecycle observers may also be used so that an object receives notification when the lifecycle state of another object changes. This is the technique used behind the scenes by the ViewModel component to identify when an observer has restarted or been destroyed. This functionality is not limited to Android framework...