Having troubles with error in AsyncTask

Question

I have few problems with syntax errors here. Below I have an alertDialog with sharedPreference and if you are wonder why I have this in a asynctask you can see this Shared Prefence for alert dialog is making my application non responsive But the syntax problem is underneath installed in my onPostExecute and it says "installed cannot be resovled to a variable." I also have another one under settings in my onPostExecute that says the same thing as well. I know this may seem like an easy fix to some people but I find this really complicated for someone like me. I also advice you look at the link if you have a better method than the AsyncTask and onResume()

@Override
protected void onResume() {

    class asynctask extends AsyncTask<String, String, String> {

        @Override
        protected String doInBackground(String... arg0) {
            final SharedPreferences settings = getSharedPreferences("pref_name", 0);
            boolean installed = settings.getBoolean("installed", false);

            return null;
        }}}

    protected void onPostExecute(String file_ad) {

        if(!installed){

            final AlertDialog.Builder alertDialog = new AlertDialog.Builder(this);

            alertDialog.setTitle("Title");
            alertDialog.setIcon(R.drawable.ic_launcher);
            alertDialog.setAdapter(new MyAdapter(), null);

            alertDialog.setPositiveButton("OK", new DialogInterface.OnClickListener() {

                public void onClick(DialogInterface dialog, int which) {
                    SharedPreferences.Editor editor = settings.edit();
                    editor.putBoolean("installed", true);
                    editor.commit();

                }
            });

            alertDialog.show();
    }
    super.onResume();
}

See my answer in your linked question. Hopefully that will clear it up. I don't know why you were told that you can't do any operations in `onCreate()` that's ridiculous. There is no need for `AsyncTask` in this situation. — codeMagic, Sep 16 '13 at 23:00

jbihan · Answer 1 · 2013-09-16T23:37:02.440

installed is declared only in doInBackground, so it's not visible into onPostExecute.

Instead of returning a String in doInBackground (where in fact you always return null), you should return a boolean (which would be installed), and in onPostExecute change the parameter for a boolean and test it instead of testing installed.

EDIT

Taking more time to update my answer :

First, I agree with @codeMagic, you definitely DON'T need an AsyncTask to do that !

But if you really want to do it this way, here is how you could do it : first, you should change the signature of your AsyncTask this way :

class asynctask extends AsyncTask<String, String, Boolean> {

Then in doInBackground, change the return value and instead of returning null, return installed :

@Override
protected boolean doInBackground(String... arg0) {
        final SharedPreferences settings = getSharedPreferences("pref_name", 0);
        boolean installed = settings.getBoolean("installed", false);

        return installed;
}}}

And finally, change the parameter of onPostExecute to accept a boolean :

protected void onPostExecute(boolean installed) {

This way, you can test installed in your method.

Actually, the return type should be `Boolean` because of the use of generics. — Hugo Hideki Yamashita, Sep 16 '13 at 23:09

Abdullah Jibaly · Answer 2 · 2013-09-16T23:12:51.733

The installed variable is local to the doInBackground method, onPostExecute cannot see it. You can either add an instance variable:

class asynctask extends AsyncTask<String, String, String> {
  boolean installed = false;
  @Override protected String doInBackground(String... arg0) {
    installed = true;
  }
}

Or, you can change the signature of your Async Task so that it returns a boolean, then simply return installed from doInBackground and it will be passed in as the parameter to onPostExecute:

class asynctask extends AsyncTask<String, String, Boolean> {
  @Override protected Boolean doInBackground(String... arg0) {
    return true;
  }
  protected void onPostExecute(Boolean installed) {
  }
}

Having troubles with error in AsyncTask

2 Answers2