Android : Multiple Requests in Parallel

I have some JSON resources like below

http://example.com?page=1

http://example.com?page=2

. . .

http://example.com?page=20

I am using AsyncTask and requesting each page within my OnPostExecute method and calling doinBackground method of the same class;

    @Override
    protected void onPostExecute(ArrayList<MyClass> result) {
        currentPage++;
        if(currentPage == 21){
            Intent intent = new Intent(getApplicationContext(), MyActivity.class);
            intent.putParcelableArrayListExtra("List", result);
            startActivity(intent);

        }
        else{
            new DownloadInfoTask().execute(this.URL + "&page=" + currentPage);
        }
   }

It seems working for me so far even if each thread is waiting for the previous ones completion. My question is would it be a better approach if i use parallel execution for consuming these kinds of resources and how can i implement parallel execution to my problem?