What is the file name used by default shared preferences?

Question

Android Backup Service requires a filename to backup shared preferences:

public static final String PREFS = "PrefFile";    
SharedPreferencesBackupHelper helper = new SharedPreferencesBackupHelper(this, PREFS);

It is clear what to use if filename is given during preferences creation like

public static final String PREF_FILE_NAME = "PrefFile";
SharedPreferences preferences = getSharedPreferences(PREF_FILE_NAME, MODE_PRIVATE);

But I use default shared preferences:

SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);

What should I pass as PREFS value to SharedPreferencesBackupHelper?

Answer 1

private static String getDefaultSharedPreferencesName(Context context) {
    return context.getPackageName() + "_preferences";
}

see your package name in AndroidManifest.xml

Answer 2

From the source code, The PackageName is based on the context that you pass in.

private static String getDefaultSharedPreferencesName(Context context) {
    return context.getPackageName() + "_preferences";
}

Answer 3

The default preference file's name is the calling activity's class name.

https://developer.android.com/reference/android/app/Activity.html#getPreferences(int)