Book Image

Android Studio 4.1 Development Essentials – Kotlin Edition

By : Neil Smyth
Book Image

Android Studio 4.1 Development Essentials – Kotlin Edition

By: Neil Smyth

Overview of this book

Android 11 has a ton of new capabilities. It comes up with three foci: a people-centric approach to communication, controls to let users quickly access and manage all of their smart devices, and privacy to give users more ways to control how data on devices is shared. This book starts off with the steps necessary to set up an Android development and testing environment, followed by an introduction to programming in Kotlin. An overview of Android Studio and its architecture is provided, followed by an in-depth look at the design of Android applications and user interfaces using the Android Studio environment. You will also learn about the Android architecture components along with some advanced topics such as touch screen handling, gesture recognition, the recording and playback of audio, app links, dynamic delivery, the AndroidStudio profiler, Gradle build configuration, and submitting apps to the Google Play Developer Console. The concepts of material design are also covered in detail. This edition of the book also covers printing, transitions, and cloud-based file storage; foldable device support is the cherry on the cake. By the end of this course, you will be able to develop Android 11 Apps using Android Studio 4.1, Kotlin, and Android Jetpack. The code files for the book can be found here: https://www.ebookfrenzy.com/retail/as41kotlin/index.php
Table of Contents (95 chapters)
95
Index

44.3 Saving and Restoring State

An object or value can be saved from within the ViewModel by passing it through to the set() method of the SavedStateHandle instance, providing the key string by which it is to be referenced when performing a retrieval:

val NAME_KEY = "Customer Name"

 

savedStateHandle.set(NAME_KEY, customerName)

When used with LiveData objects, a previously saved value may be restored using the getLiveData() method of the SavedStateHandle instance, once again referencing the corresponding key as follows:

var restoredName: LiveData<String> = savedStateHandle.getLiveData(NAME_KEY)

To restore a normal (non-LiveData) object, simply use the SavedStateHandle get() method:

var restoredName: String? = savedStateHandle.get(NAME_KEY)

Other useful SavedStateHandle methods include the following:

contains(String key) - Returns a boolean value indicating whether the saved state contains a value for the specified key.

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