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

61.9 Returning Data from a Sub-Activity

ActivityB is now launched as a sub-activity of MainActivity, which has, in turn, been modified to handle data returned from ActivityB. All that remains is to modify ActivityB.kt to implement the finish() method and to add code for the answerQuestion() method, which is called when the “Answer Question” button is touched. The finish() method is triggered when an activity exits (for example when the user selects the back button on the device):

fun answerQuestion(view: View) {

    finish()

}

 

override fun finish() {

    val data = Intent()

 

    val returnString = editText1.text.toString()

    data.putExtra("returnData", returnString)

 

    setResult(RESULT_OK, data)

    super.finish()

}

All that the finish() method needs to do is create a new intent...