android - How to parse my json data? -

I'm starting in Android and I want to get data from the server and show data in the data view. I get the data correctly from the server and show the result in toast, but my data is:

  [{"countryname": "China", "calculation" : "200"}]  

How can I parse that result in this block?
For example: countryname = China

  @Override protected void OnPostExecute (string result) {//Toast.makeText (getBaseContext (), "Data sent! ", Toast.LNGTH_LONG). Show (); //Log.d (I have my backup backup: "result.toString ()); try {JSONObject jsonObj = new JSONObject (result);} hold (JasonXExtension) {e.printStackTrace ();}}  

Please do not show me the link to the tutorial or any other site, please write your code. Thanks for all.