java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View .MainActivity.findViewById(int)' on a null object reference

Question

I have a class called MainActivity.java that call an AsyncTask class. The last class have a findViewById() that in execution retur

Answer 1

put imageview as a variable of your class

private ImageView image;

on your onCreate initialize

image = (ImageView) findViewById(R.id.image);


public class Connection extends AsyncTask {
        public String result;

        //I know, this isn't correct, how can i do?
        public MainActivity MainActivity;

        @Override
        protected String doInBackground(String... arg0) {
        // TODO Auto-generated method stub
            //...

        return "a string";
    }

    protected void onPostExecute(String result) {
        super.onPostExecute(result);
                //...

        // Where the error is generated
        //do other stuff with your imageview

        //...

    }
}