Data Storage

A typical desktop operating system provides a common file system that any application can use to store files that can be read by other applications (perhaps with some access control settings). Android uses a different system: On Android, all application data (including files) are private to that application.

However, Android also provides a standard way for an application to expose its private data to other applications — through content providers. A content provider is an optional component of an application that exposes read/write access to the application's data, subject to whatever restrictions it might impose. Content providers implement a standard syntax for requesting and modifying data, and a standard mechanism for reading the returned data. Android supplies a number of content providers for standard data types, such as image, audio, and video files and personal contact information. For more information on using content providers, see a separate document, Content Providers.

Whether or not you want to export your application's data to others, you need a way to store it. Android provides the following four mechanisms for storing and retrieving data: Preferences, Files, Databases, and Network.

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