How do I get sharedpreferences in Asynctask?

Question

I am writing an android application for my school project but i am stuck here. The problem is i have to access a SharedPreferences value and need it in an

Answer 1

You can get SharedPreferences in the background using an AsyncTask.

The mistake is in this line, where you are passing in the wrong type of variable:

SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);

In your case, the word this refers to the AsyncTask instance that you are calling if from.

---

What I do is I pass the Context in to the task in the execute() method. See the code below for a working example:

    new AsyncTask<Context, Void, String>()
    {
        @Override
        protected String doInBackground(Context... params)
        {
            Context context = params[0];
            SharedPreferences prefs =
                    context.getSharedPreferences("name of shared preferences file",
                            Context.MODE_PRIVATE);

            String myBackgroundPreference = prefs.getString("preference name", "default value");

            return myBackgroundPreference;
        }

        protected void onPostExecute(String result)
        {
            Log.d("mobiRic", "Preference received in background: " + result);
        };

    }.execute(this);

In the above example, this refers to the Activity or Service that I call this from.

Answer 2

You can get SharedPreferences in a background thread using the PreferenceManager like this:

SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(<YourActivity>.this);

Answer 3

Override onPreExecute or onPostExecute method of AsyncTask and get SharedPreferences there:

@Override
protected void onPreExecute() {
    super.onPreExecute();
    //get sharedPreferences here
    SharedPreferences sharedPreferences = getSharedPreferences(<SharedPreferencesName>, <Mode>);
}

Please note that getSharedPreferences is an Activity method. So, you need to call it through Context if you are not using it in Activity.