I have a JSON file and uploaded it on my server, then I fetch it in my android app. But every time i try to debug my app, it crashes with Null Pointer Exception in the AsyncTask class and gives me this error:
10-30 05:07:46.268 8710-9073/com.example.prof_mohamedatef.listview E/AndroidRuntime:
FATAL EXCEPTION: AsyncTask #1
java.lang.RuntimeException: An error occured while executing doInBackground()
at android.os.AsyncTask$3.done(AsyncTask.java:299)
at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
at java.util.concurrent.FutureTask.run(FutureTask.java:239)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
at java.lang.Thread.run(Thread.java:856)
Caused by: java.lang.NullPointerException
at com.example.prof_mohamedatef.listview.androidlistviewactivity$FetchUsersDesires.doInBackground(androidlistviewactivity.java:159)
at com.example.prof_mohamedatef.listview.androidlistviewactivity$FetchUsersDesires.doInBackground(androidlistviewactivity.java:84)
at android.os.AsyncTask$2.call(AsyncTask.java:287)
at java.util.concurrent.FutureTask.run(FutureTask.java:234)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
at java.lang.Thread.run(Thread.java:856)
I am assured that my devices is connected to the internet. I adopt in url which may be built wrongly, it may requires question mark ? or any other symbols, or my json file may be hasn't constructed correctly. Please review my url : https://yourbest-online.com/images/xml_files/Desires.json and my json code:
{"page":1,"Desires": [{
"hotels": {
"id": "1",
"title": "hotels booking",
"thumb_url": "https://yourbest-online.com/images/xml_files/hotels.png"
},
"Aviation": {
"id": "2",
"title": "Aviation Tickets Booking",
"thumb_url": "https://yourbest-online.com/images/xml_files/aviation.png"
}
],"total_results":2,"total_pages":1}
This is all of my AsyncTask Class including doInBackground method where the problem always occur :
public class FetchUsersDesires extends AsyncTask<String, Void, ArrayList<OptionsEntity>> {
private final String LOG_TAG = FetchUsersDesires.class.getSimpleName();
private ArrayList<OptionsEntity> getUsersDesiresFromJson(String UsersDesires)
throws JSONException {
UsersDesiresJson = new JSONObject(UsersDesires);
UsersDesiresJsonAray = UsersDesiresJson.getJSONArray(main_List);
list.clear();
for (int i = 0; i < UsersDesiresJsonAray.length(); i++) {
// Get the JSON object representing a movie per each loop
oneOptionData = UsersDesiresJsonAray.getJSONObject(i);
ID_STRING = oneOptionData .getString(ID);
TITLE_STRING = oneOptionData .getString(TITLE);
Image_URL_STRING = oneOptionData .getString(Image_URL);
mAdapter=null;
OptionsEntity entity = new OptionsEntity(Image_URL_STRING, TITLE_STRING);
list.add(entity);
}
return list;
}
@Override
protected ArrayList<OptionsEntity> doInBackground(String... params) {
String UsersDesires_JsonSTR = null;
HttpURLConnection urlConnection = null;
BufferedReader reader = null;
if (params.length == 0) {
return null;
}
try {
URL url = new URL(params[0]);
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
InputStream inputStream = urlConnection.getInputStream();
StringBuffer buffer = new StringBuffer();
if (inputStream == null) {
UsersDesires_JsonSTR = null;
}
reader = new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
buffer.append(line + "\n");
}
if (buffer.length() == 0) {
return null;
}
UsersDesires_JsonSTR = buffer.toString();
Log.v(LOG_TAG, "Users Desires String: " + UsersDesires_JsonSTR);
} catch (IOException e) {
Log.e(LOG_TAG, "Error here Exactly ", e);
return null;
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (reader != null) {
try {
reader.close();
} catch (final IOException e) {
Log.e(LOG_TAG, "Error closing stream", e);
}
}
}
try {
return getUsersDesiresFromJson(UsersDesires_JsonSTR);
} catch (JSONException e) {
Log.e(LOG_TAG, "didn't got Users Desires from getJsonData method", e);
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(ArrayList<OptionsEntity> result) {
if (result != null&& getApplicationContext()!=null) {
mAdapter = new LazyAdapter(getApplicationContext(),R.layout.list_row, result);
listView.setAdapter(mAdapter);
}
}
}
Note , Connection now is running on the best way, but JSON Exception appear says : "No Value for id" and the json String variable value in android studio looks like that : "{"page":1,"Desires": [{ "hotels": { "id": "1", "title": "hotels booking", "thumb_url": "https://yourbest-online.com/images/xml_files/hotels.png" }, "Aviation": { "id": "2", "title": "Aviation Tickets Booking", "thumb_url": "https://yourbest-online.com/images/xml_files/aviation.png" } }],"total_results":2,"total_pages":1} " the value looks like to include multiple \n\t\t\t symbols for each space, i think this my causing the problem, any advise for this purpose please.
your help will be appreciated. thank you
