Asynctask not working on SDK 23 or before

Question

Good day, for what the problem I met now, my asynctask is working for SDK 24 or above,but when I put it on SDK 21,22,23 emulator and real devices, it doen't work.

The weird thing is: 1.) Asynctasks on my first activity and fragment are working, but the 2nd activity's asysntask is not working,error code: 400, exception java.lang.IllegalStateException : myURL.

My asynctask with doInBackGround code:

        @Override
        protected String doInBackground(Void... voids) {
                try {
                    //creating a URL
                    URL url = new URL(urlWebService);
                    //Opening the URL using HttpURLConnection
                    HttpURLConnection con = (HttpURLConnection) url.openConnection();

                    //StringBuilder object to read the string from the service
                    StringBuilder sb = new StringBuilder();

                    //We will use a buffered reader to read the string from service
                    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(con.getInputStream()));

                    //A simple string to read values from each line
                    String json;

                    while ((json = bufferedReader.readLine()) != null) {
                        if (!json.contains("<br")) {
                            sb.append(json + "\n");
                        }
                    }

                    //finally returning the read string
                    return sb.toString().trim();

                } catch (Exception e) {
                    System.out.println("Error in http connection " + e.toString());
                    return null;
                }
        }
    }

For this code, works on SDK 24,25,26. and it will throw an exception at con.getInputStream(). I am not sure what is the problem. Is it thread or what other problems? Thanks.

IOExeption
10-27 02:28:29.453 16954-17698/com.example.reonyx.tracking5 W/System.err: java.io.FileNotFoundException:mrURL
10-27 02:28:29.453 16954-17698/com.example.reonyx.tracking5 W/System.err:     at com.android.okhttp.internal.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:197)
10-27 02:28:29.453 16954-17698/com.example.reonyx.tracking5 W/System.err:     at com.example.reonyx.tracking5.PlayBackActivity$1GetJSON.doInBackground(PlayBackActivity.java:1206)
10-27 02:28:29.453 16954-17698/com.example.reonyx.tracking5 W/System.err:     at com.example.reonyx.tracking5.PlayBackActivity$1GetJSON.doInBackground(PlayBackActivity.java:964)
10-27 02:28:29.453 16954-17698/com.example.reonyx.tracking5 W/System.err:     at android.os.AsyncTask$2.call(AsyncTask.java:288)
10-27 02:28:29.453 16954-17698/com.example.reonyx.tracking5 W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
10-27 02:28:29.454 16954-17698/com.example.reonyx.tracking5 W/System.err:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
10-27 02:28:29.454 16954-17698/com.example.reonyx.tracking5 W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
10-27 02:28:29.454 16954-17698/com.example.reonyx.tracking5 W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
10-27 02:28:29.454 16954-17698/com.example.reonyx.tracking5 W/System.err:     at java.lang.Thread.run(Thread.java:818)

Answer 1

Is it aynctask not working or HttpURLConnection is not working as expected ? I can understand as per code you are using the get url to retrive the data.

I can suggest to use getResponseCode method to wait for the response and then try to use getInputStream method.

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

    URL url;
    HttpURLConnection urlConnection = null;

    try {
        url = new URL(strings[0]);
        urlConnection = (HttpURLConnection) url.openConnection();

        int responseCode = urlConnection.getResponseCode();

        if(responseCode == HttpURLConnection.HTTP_OK) {

          // use bufferreder to get the data from input stream.

        }

    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
       if(urlConnection!=null)
         urlConnection.disconnect();
    } 

    return null;
}