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

78.8 Gaining Persistent Access to a File

When an application gains access to a file via the Storage Access Framework, the access will remain valid until the Android device on which the application is running is restarted. Persistent access to a specific file can be obtained by “taking” the necessary permissions for the Uri. The following code, for example, persists read and write permissions for the file referenced by the fileUri Uri instance:

val takeFlags = (intent.flags and (Intent.FLAG_GRANT_READ_URI_PERMISSION

                                       or Intent.FLAG_GRANT_WRITE_URI_PERMISSION)

 

contentResolver.takePersistableUriPermission(fileUri, takeFlags)

Once the permissions for the file have been taken by the application, and assuming the Uri has been...