Book Image

Android Studio 4.0 Development Essentials - Kotlin Edition

By : Neil Smyth
Book Image

Android Studio 4.0 Development Essentials - Kotlin Edition

By: Neil Smyth

Overview of this book

Kotlin as an Android-compatible programming language is becoming increasingly popular. Fully updated for Android Studio 4.0, this book will teach you the skills necessary to develop Android-based applications using Kotlin. Starting with the basics, this book outlines the steps necessary to set up Android development and testing environments, and goes on to introduce you to programming in Kotlin. You’ll practice Java to Kotlin code conversion and explore data types, operators, expressions, loops, functions, as well as the basics of OOP in Kotlin. You’ll then learn about Android architecture components and advanced topics, such as intents, touchscreen handling, gesture recognition, multi-window support integration, and biometric authentication. As you make progress, you’ll explore Android Studio 4.0’s key features, including layout editor, direct reply notifications, and dynamic delivery. You’ll also delve into Android Jetpack and create a sample app project using ViewModel, the Android Jetpack component. Finally, you will upload your app to Google Play Console and model the build process using Gradle. By the end of this Android book, you’ll be fully prepared to develop applications using Android Studio 4.0 and Kotlin.
Table of Contents (97 chapters)
97
Index

45.4 Lifecycle States and Events

When the status of a lifecycle owner changes, the assigned Lifecycle object will be updated with the new state. At any given time, a lifecycle owner will be in one of the following five states:

Lifecycle.State.INITIALIZED

Lifecycle.State.CREATED

Lifecycle.State.STARTED

Lifecycle.State.RESUMED

Lifecycle.State.DESTROYED

As the component transitions through the different states, the Lifecycle object will trigger events on any observers that have been added to the list. The following events are available for implementation within the lifecycle observer:

Lifecycle.Event.ON_CREATE

Lifecycle.Event.ON_START

Lifecycle.Event.ON_RESUME

Lifecycle.Event.ON_PAUSE

Lifecycle.Event.ON_STOP

Lifecycle.Event.ON_DESTROY

Lifecycle.Event.ON_ANY

Annotations are used within the observer class to associate methods with lifecycle events. The...