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Android - Basic Steps (Data Management)

SharedPreferences

  • Persistent Map of simple data types
  • Automatically persisted across application sessions
  • Used for store long-term storage of customizable application data

Get a SharedPreferences object

  • Activity.getPreferences(int mode)

Get a specific SharedPreferences

  • Context.getSharedPreferences(String file, int mode)
    • file - name of SharedPreference file
  • Get Values
    • getAll()
    • getBoolean(...)
    • getString(...)

Write SharedPreferences

  • SharedPreferences.edit()
    • putInt(...)
    • putString(...)
    • remove(...)

Save changes

  • SharedPreferences.Editor.commit()

PreferenceFragment

  • Display user preferences that can be modified

Memomry

  • Internal
    • Application private data sets
  • External
    • non-private data sets
    • Determine the status of external memory
      • Environment.getExternalStorageState()
      • Results
        • MEDIA_MOUNTED
        • MEDIA_MOUNTED_READ_ONLY
        • MEDIA_REMOVED
    • Permission
      • android.permission.WRITE_EXTERNAL_STORAGE

Cache Files

Get an instance
  • File Context.getCacheDir()
    • Return absolute path to an application-specific directory for temporary files
  • Context.getExternalCacheDir()
    • Returns a dile representing external storage directory for cache files

SQLite

Designed to operate < 300 kb

  • Use as recomendation a helper SQLiteOpenHelper
  • Follow the next steps
    • Create a subclass
    • Call method super() to initialize underlying DB
    • Override onCreate()
      • Create the tables using CREATE TABLE
    • Override onUpgrade()
    • Use SQLiteOpenHelper methods to open the DB
    • Execute operations
  • DB Path
    • /data/data/<package name>/databases
SQLITE3
  • Use to examine the DB
    • #adb -s emulator-5554 shell
  • Open the connection
    • #sqlite3 /data/data/<package name>/databases/<DB_name>
    • <package name> - course.examples.DataManagement.Data.BaseExample
    • <DB_name> - artist_dbd

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