SharedPreferences will not save/load in PreferenceActivity

Question

EDIT: The problem described below was due to a very peculiar device issue not caused by any coding-related problem.

I have a preferenceActi

Answer 1

I too had a problem with saving and then retrieving data. I had my Save and Load code in a class that extends Application because I wanted a single instance of my data. I could see the String being saved, no errors in LogCat and yet when I try to load it, again with no error, my String is empty. I never checked whether the data actually went into the file so I have no idea whether there was a failure on Save or Load or both.

My code was more or less as follows: (comboToSave is simply a string generated by Gson from a simple data class)

in one method to save:

  SharedPreferences sharedPref = activity.getPreferences(Context.MODE_PRIVATE); 
  SharedPreferences.Editor editor = sharedPref.edit();
  editor.putString(getString(R.string.prefCombos), comboToSave); 
  editor.commit();

in another method to load:

  SharedPreferences sharedPref = activity.getPreferences(Context.MODE_PRIVATE);
  String loadedComboText = sharedPref.getString(getString(R.string.prefCombos), "");

After lots of head scratching and not knowing what to do I changed the code that retrieves the sharedPref value from

SharedPreferences sharedPref = activity.getPreferences(Context.MODE_PRIVATE);

to

SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());

There is some more here on the difference between the two (although in my case it seems exactly the same)

Still the result on my Galaxy S3 was the same. However, testing both versions on other devices, including VDs (virtual devices) worked.

In the first version of the code I passed the Activity from the calling activity; for save from the activity where the final bit of data is collected from the user, and for loading from my main activity so that I had it ready when the app is started.

I played with uninsalling the app and re-intalling, turning the device off and on again last night to no avail.

I have now moved the save and load methods from the application class to the activity where I complete the input i.e. both load and save code is now in the same activity. I have tested this with both variations of the code and they both work. I get back what I save. I then moved all the code back to the Application class and it works; this leads me to believe that somehow with all the installing/uninstalling I somehow managed to get it working. Point is: the code is correct - if it does not work the device and/or settings are probably to blame