How to use AsyncTask correctly in Android [closed]

I don't want to pass any arguments to doInBackground method of the AsyncTask.

So what should be the code like?

Solution 1:

import android.app.Activity;
import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.os.Bundle;

public class AsyncExample extends Activity{


private String url="http://www.google.co.in";

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}


@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();

    new AsyncCaller().execute();

}

private class AsyncCaller extends AsyncTask<Void, Void, Void>
{
    ProgressDialog pdLoading = new ProgressDialog(AsyncExample.this);

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        //this method will be running on UI thread
        pdLoading.setMessage("\tLoading...");
        pdLoading.show();
    }
    @Override
    protected Void doInBackground(Void... params) {

        //this method will be running on background thread so don't update UI frome here
        //do your long running http tasks here,you dont want to pass argument and u can access the parent class' variable url over here


        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        super.onPostExecute(result);

        //this method will be running on UI thread

        pdLoading.dismiss();
    }

    }
}

Solution 2:

According to AsyncTask, its

 AsyncTask<Params, Progress, Result>

• Params, the type of the parameters sent to the task upon execution.
• Progress, the type of the progress units published during the background computation.
• Result, the type of the result of the background computation.

So if you want to pass void in doInBackground just pass void in place of Params.

Example code:

class DownloadLink extends AsyncTask<Void, Void, Void> {


        @Override
        protected Void doInBackground(Void... params) {
            // TODO Auto-generated method stub

            //Do Your stuff here..
            return null;
        }
    }

And call it as:

 new DownloadLink().execute();

Solution 3:

Create your AsyncTask class as if you don't want to pass any parameter to doInBackground :

 public class LongOperation extends AsyncTask<Void, Void, String> {


          public LongOperation(Context context) {

          }

          @Override
          protected void onPreExecute() {

          }

          @Override
          protected String doInBackground(Void... params) {

              return null;
          }      

          @Override
          protected void onPostExecute(String result) {                           

          }
    }

and start AsyncTask as without passing any parameter to execute :

   LongOperation longOperation = new LongOperation(this);
   longOperation.execute();