Android Data Storage

Android Data Storage

Android provides several ways to store the data. More details can be found from http://developer.android.com/guide/topics/data/data-storage.html

• Shared Preferences
• This provides a quick and easy way to store key-value pair based primitive data across multiple sessions of the app; DOES NOT preserve the data across power cycle.
• Examples/Tutorials
• http://www.vogella.com/articles/AndroidFileBasedPersistence/article.html
• Internal Storage
• Stores the data on the internal storage of the phone. Preserves the data across the power cycles.
• Files created gets removed when the user uninstalls the app
• This data is app-specific data; Not world readable
• E.g. Example of Internal Storage on Android
• External Storage (e.g. SD Card)
• This is saved/restored in similar way as the internal storage
• HOWEVER -- IT IS WORLD READABLE; So do not save sensitive data
• E.g. External Storage example on Android
• SQLite Databases
• Android has full support for SQLite
• Any database created in the app, can be accessed by the name from any class in the app
• Not outside the app
• To Create a new database, create a subclass of SQLiteOpenHelper
• E.g. 
• http://www.vogella.com/articles/AndroidSQLite/article.html
• http://www.androidhive.info/2011/11/android-sqlite-database-tutorial/
• Cloud storage
• 
  
• Content provider
• It is the only way to share the data across multiple apps - selectively
• Content provider and Content resolver provides an interface to the app to talk to the Contents, which could be SQLite database or Internal/External storage or on cloud
• Managed Queries is another important concept to understand with ContentProvider with the queries; Managed Queries based cursor will get updated automatically as and when the activity goes through it's life cycle
• Good Blog: http://www.vogella.com/articles/AndroidSQLite/article.html#contentprovider