Book Image

Android Studio 3.5 Development Essentials - Java Edition

By : Neil Smyth
Book Image

Android Studio 3.5 Development Essentials - Java Edition

By: Neil Smyth

Overview of this book

Android applications have become an important part of our daily lives and lots of effort goes into developing an Android application. This book will help you to build you own Android applications using Java. Android Studio 3.5 Development Essentials – Java Edition first teaches you to install Android development and test environment on different operating systems. Next, you will create an Android app and a virtual device in Android Studio, and install an Android application on emulator. You will test apps on physical Android devices, then study Android Studio code editor and constraint layout, Android architecture, the anatomy of an Android app, and Android activity state changes. The book then covers advanced topics such as views and widgets implementation, multi-window support integration, and biometric authentication, and finally, you will learn to upload your app to Google Play console and handle the build process with Gradle. By the end of this book, you will have gained enough knowledge to develop powerful Android applications using Java.
Table of Contents (86 chapters)
86
Index

68.8 Opening and Reading a Storage File

Having written the code to create and save text files, the final task is to add some functionality to open and read a file from the storage. This will involve writing the openFile() onClick event handler method and implementing it so that it starts an ACTION_OPEN_DOCUMENT intent:

public void openFile(View view)

{

       Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);

       intent.addCategory(Intent.CATEGORY_OPENABLE);

       intent.setType("text/plain");

       startActivityForResult(intent, OPEN_REQUEST_CODE);

}

In this code, the intent is configured to filter selection to files which can be opened by the application. When the activity is started, it is passed the open request code constant which will now need to be handled within the onActivityResult() method...