Changes

Working with files in the Storage Access Framework involves triggering a variety of intents depending on the specific action to be performed. Invariably this will result in the framework displaying the storage picker user interface so that the user can specify the storage location (such as a directory on Google Drive and the name of a file). When the work of the intent is complete, the application will be notified by a call to a method named onActivityResult().

Since all intents from a single activity will result in a call to the same onActivityResult() method, a mechanism is required to identify which intent triggered the call. This can be achieved by passing a request code through to the intent when it is launched. This code is then passed on to the onActivityResult() method by the intents enabling the method to identify which action has been requested by the user. Before implementing the onClick handlers to create, save and open files, the first step is to declare some request codes for these three actions.

The code in this method is largely straightforward. The result of the activity is checked and, if successful, the request code is compared to the CREATE_REQUEST_CODE value to verify that the user is creating a new file. That being the case, the edit text view is cleared of any previous text to signify the creation of a new file.

Compile and run the application and select the New button. The Storage Access Framework should subsequently display the “Save to” storage picker user interface as illustrated in Figure 52 2.

The text entered by the user is extracted from the edit text object and written to the output stream before both the file descriptor and stream are closed. Code is also added to handle any IO exceptions encountered during the file writing process.

With the new method added, compile and run the application, enter some text into the text area and select the Save button. From the picker interface, locate the previously created file from the Google Drive storage to save the text to that file. Return to your Google Drive account in a browser window and select the text file to display the contents. The file should now contain the text entered within the StorageDemo application on the Android device.

The new code added above to handle the open request obtains the Uri of the file selected by the user from the picker user interface and passes it through to a method named readFileContent() which is expected to return the content of the selected file in the form of a String object. The resulting string is then assigned to the text property of the edit text view. Clearly, the next task is to implement the readFileContent() method:

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package com.ebookfrenzy.storagedemo;