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

43.6 Assigning the ViewModel Instance to the Data Binding Variable

At this point, the data binding knows that it will be binding to an instance of a class of type MainViewModel but has not yet been connected to an actual MainViewModel object. This requires the additional step of assigning the MainViewModel instance used within the app to the viewModel variable declared in the layout file. Since the reference to the ViewModel is obtained in the onActivityCreated() method, it makes sense to make the assignment there:

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import com.ebookfrenzy.viewmodeldemo.BR.myViewModel

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.

override fun onActivityCreated(savedInstanceState: Bundle?) {

    super.onActivityCreated(savedInstanceState)

    viewModel = ViewModelProviders.of(this).get(MainViewModel::class.java)

 

    binding.setVariable(myViewModel, viewModel)

}

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.

If Android Studio reports myViewModel as undefined, rebuild the project...