77.3 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:
val OPEN_REQUEST_CODE = 41
val intent = 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 intent using the CATEGORY_OPENABLE option...