Value null of type org.json.JSONObject$1 cannot be converted to JSONObject

In the data you receive weather is a JSONArray.

Try this :

 String json = "{\"coord\":{\"lon\":-0.13,\"lat\":51.51},\"weather\":[{\"id\":800,\"main\":\"Clear\",\"description\":\"clear sky\",\"icon\":\"01d\"}],.....}";

try{
    JSONObject jo = new JSONObject(json);
    JSONArray weather = jo.getJSONArray("weather");
    for(int i = 0;i < weather.length(); i++){
        JSONObject w = weather.getJSONObject(i);
        String main = w.getString("main");
        String description = w.getString("description");
        //...
    }
}catch (Exception e){

}

As you said if the result returned by the server start with null you will have this exception org.json.JSONException: Value null of type org.json.JSONObject$1 cannot be converted to JSONObject.

This is because this result is not a valid JSON content.

If you really receive this invalid content from the server a workaround can be to remove the null before parsing the JSON.

String crappyPrefix = "null";

if(result.startsWith(crappyPrefix)){
    result = result.substring(crappyPrefix.length(), result.length());
}
JSONObject jo = new JSONObject(result);

Try This (worked for me).. I was having same problem

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

        HttpURLConnection httpURLConnection =null;
        URL url;


String resultString="";  <------- instead of setting it to null


        @Override
        protected String doInBackground(String... urls) {


            try {
                url = new URL(urls[0]);
                httpURLConnection = (HttpURLConnection) url.openConnection();
                InputStream is = httpURLConnection.getInputStream();
                InputStreamReader isr = new InputStreamReader(is);
                int data = isr.read();
                while(data != -1){
                    char ch = (char) data;
                    resultString += ch;
                    data = isr.read();

                }
                return resultString;



            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }


            return null;
        }

some times the problem is your response is null, but you expect a JSONObject. its bettter to resolve it in server side.if you can not edit server side code, this question and this one may be useful