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

67.3 Filtering Picker File Listings

The files listed within the picker user interface when an intent is started may be filtered using a variety of options. Consider, for example, the following code to start an ACTION_OPEN_DOCUMENT intent:

private static final int OPEN_REQUEST_CODE = 41;

 

Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT);

startActivityForResult(intent, OPEN_REQUEST_CODE);

When executed, the above code will cause the picker user interface to be displayed, allowing the user to browse and select any files hosted by available document providers. Once a file has been selected by the user, a reference to that file will be provided to the application in the form of a Uri object. The application can then open the file using the openFileDescriptor(Uri, String) method. There is some risk, however, that not all files listed by a document provider can be opened in this way. The exclusion of such files within the picker can be achieved by modifying the...