How to assign global variables with AsyncTask

Issue

Here I've given a small example of the problem I'm facing with global variables and AsyncTasks. I've gone and read in data from a file and assigned that data to a string and in the onPostExecute() method I assigned that string to the global variable. However when I assign the TextView with the "aString" variable, the output is still "nothing".

I know that if you do the TextView assigning in the onPostExecute() method it works however what if I want to use the data in methods outside of the AsyncTask.

Can someone please help with this, I think I'm not getting something?

public class GoodAsync extends Activity{

    TextView tv;
    String aString = "nothing";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.asynctasks);

        new AsyncTasker().execute();

        tv = (TextView) findViewById(R.id.async_view);
        tv.setText(aString);

    }

    private class AsyncTasker extends AsyncTask<String, Integer, String>{

        @Override
        protected String doInBackground(String... arg0) {

            AssetManager am = GoodAsync.this.getAssets();
            String string = "";
            try {
                // Code that reads a file and stores it in the string variable

                return string;

            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);
            aString = result;
        }   

    }
}

Solution

Perhaps you want to do it like this:

public class GoodAsync extends Activity{

TextView tv;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.asynctasks);
    tv = (TextView) findViewById(R.id.async_view);
    new AsyncTasker().execute();
}

    public void setTextView (String text) {
       tv.setText(text);
    }

    private class AsyncTasker extends AsyncTask<String, Integer, String>{

        ....

        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);
            setTextView(result);
        }   

    }
}

Answered By - DieselPower