Book Image

Android Studio 4.0 Development Essentials - Java Edition

By : Neil Smyth
Book Image

Android Studio 4.0 Development Essentials - Java Edition

By: Neil Smyth

Overview of this book

Android rolls out frequent updates to meet the demands of the dynamic mobile market and to enable its developer community to lead advancements in application development. This book focuses on the updated features of Android Studio (the fully integrated development environment launched by Google) to build reliable Android applications using Java. The book starts by outlining the steps necessary to set up an Android development and testing environment. You’ll then learn how to create user interfaces with the help of Android Studio Layout Editor, XML files, and by writing the code in Java. The book introduces you to Android architecture components and advanced topics such as intents, touchscreen handling, gesture recognition, multi-window support integration, and biometric authentication, and lets you explore key features of Android Studio 4.0, including the layout editor, direct reply notifications, and dynamic delivery. You’ll also cover Android Jetpack in detail and create a sample app project using the ViewModel component. Finally, you’ll upload your app to the Google Play Console and handle the build process with Gradle. By the end of this book, you’ll have gained the skills necessary to develop applications using Android Studio 4.0 and Java.
Table of Contents (88 chapters)
88
Index

69.5 Reading the Content of a File

The exact steps required to read the content of a file hosted by a document provider will depend to a large extent on the type of the file. The steps to read lines from a text file, for example, differ from those for image or audio files.

An image file can be assigned to a Bitmap object by extracting the file descriptor from the Uri object and then decoding the image into a BitmapFactory instance. For example:

ParcelFileDescriptor pFileDescriptor =

            getContentResolver().openFileDescriptor(uri, "r");

 

FileDescriptor fileDescriptor =

            pFileDescriptor.getFileDescriptor();

 

Bitmap image = BitmapFactory.decodeFileDescriptor(fileDescriptor);

 

pFileDescriptor.close();

 

myImageView.setImageBitmap(image);

Note that the file descriptor is opened...