How to use Asynchronous and onPostExecute to send value to PHP and get Response

How to send value to php page using Asynchronous with HttpRequest and get a response, then do something with it using OnPostExcute for example.

Java :

private class MyAsyncTask extends AsyncTask<String, Integer, Double>{

    @Override
    protected Double doInBackground(String... params) {
        // TODO Auto-generated method stub
        postData(params[0]);
        return null;
    }

    protected void onPostExecute(Double result){
        pb.setVisibility(View.GONE);
        // Do something with the response here
        // ....
    }

    public void postData(String valueIWantToSend) {
        // Create a new HttpClient and Post Header
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("__url_to_file.php");

        // Add your data
        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
        nameValuePairs.add(new BasicNameValuePair("myHttpData", valueIWantToSend));
        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

        HttpResponse response = httpclient.execute(httppost);
    }

}

PHP :

<?php
    // return the value back to the app
    echo $_POST["myHttpData"];

?>