在Android中重新安装应用程序后检索设置

Question

I have an app which saves some settings using PreferenceManager. Later I uninstall the application and later want to retrieve the same settings back when I reinstall the same application. For eg: I have a checkbox whose state is saved using preference manager and later uninstall the app. Later when I reinstall the app I need to get the state back of that checkbox. Is this possible to do? If not with preferenceManager is there any other way to do it ie by saving in DB?

Answer 1

SharedPreference and Database won't be kept after uninstalling an app.
That being said, Android provides an easy way to send your SharedPreferences to the cloud and retrieve them when re-installing an app. This mechanism is called BackupAgentHelper .

Answer 2

You can keep a backup file for shared preferences in the external storage and when you install the application again you can update the shared preferences from the backup file. Or you can use BackupAgentHelper/SharedPreferenceBackupHelper to store the data on cloud. For the SQLite however, if you keep the database files in a different directory those will not be removed by Android when uninstalling the application. In case of a SQLite database you may set the database directory in the SQLiteOpenHelper constructor. Lets say you want the path set as:

final static String DB_PATH = Environment.getExternalStorageDirectory().getAbsolutePath().concat("/databases/my_db.db");

Then in the sqlite helper you set it as follows:

public DbHelper(Context context, String name, CursorFactory factory,
        int version) {
    super(context, DB_PATH, factory, version);
}

Meanwhile in case of the SharedPreferences you may copy the file from the default app data directory to a folder of your chosen in the sd card. You need to pay attention here in order to choose the appropriate moment when to backup the SharedPreferences file. As a IO operation it might require time to complete.