Learning Android™ Application Programming: A Hands-On Guide to Building Android Applications

Using Shared Preferences

The settings class you created saves the application’s state only while it is running. If the application is stopped and restarted, it won’t remember the previous state. To fix that, you need to use shared preferences to save the application’s state. Shared preferences allow you to save key value pairs on a device.

You can save the vibration setting—whether it’s turned on or off—as a preference:

1. Open Settings.java, and add a private static string called VIBRATE:

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private static String VIBRATE = "vibrate";

2. In the isVibrateOn method, obtain an instance of shared preferences by calling activity.getPreferences:

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SharedPreferences preferences     = activity.getPreferences(Activity. ...