java net UnknownHostException Unable to resolve host url No address associated with hostname and End of input at character 0 of

Question

I ve created an app that loads a question from my web services  and it works fine  But  sometimes it crashes and I do not get the reason why this is happening  especially because I have also given it the required permissions  It works fine  but at random  it crashes and gives me this report   private void sendContinentQuestions int id           TODO Auto-generated method stub        Get the data  see above      JSONArray json   getJSONfromURL id           try              for int i 0  i  lt  json length    i                      HashMap lt String  String gt  map   new HashMap lt String  String gt                     JSONObject jObject   json getJSONObject i                   longitude   72 5660200                  String category id   jObject getString  category id                    String question id   jObject getString  question id                    String question name   jObject getString  question name                    String latitude   jObject getString  latitude                    String longitude   jObject getString  longitude                    String answer   jObject getString  answer                    String ansLatLng   latitude     longitude                    Log v     data        question id  --  question name  -cat id-  category id  --ansLatLng   ansLatLng   answer    answer                    all question add new QuestionData game id category id question id question name ansLatLng answer                           catch JSONException e                       Log e  log tag    Error parsing data   e toString                          public JSONArray getJSONfromURL int id        String response           URL url      try           url   new URL Consts GET URL  index php Api getQuestion cat id   id           HttpURLConnection http    HttpURLConnection  url openConnection            http setRequestMethod  POST            InputStream is   http getInputStream            BufferedReader br   new BufferedReader new InputStreamReader is            response   br readLine            Log v     Response         response           http disconnect          catch  MalformedURLException e               TODO Auto-generated catch block         e printStackTrace         catch  ProtocolException e               TODO Auto-generated catch block         e printStackTrace           catch  IOException e               TODO Auto-generated catch block         e printStackTrace                 try parse the string to a JSON object     JSONArray jArray   null      try           jArray   new JSONArray response         catch JSONException e           Log e  log tag    Error parsing data   e toString                return jArray        11-13 15 02 52 307  W System err 8012   java net UnknownHostException  Unable to resolve host  www xyz com   No address associated with hostname 11-13 15 02 52 317  W System err 8012       at java net InetAddress lookupHostByName InetAddress java 424  11-13 15 02 52 317  W System err 8012       at java net InetAddress getAllByNameImpl InetAddress java 236  11-13 15 02 52 317  W System err 8012       at java net InetAddress getAllByName InetAddress java 214  11-13 15 02 52 317  W System err 8012       at libcore net http HttpConnection  lt init gt  HttpConnection java 70  11-13 15 02 52 317  W System err 8012       at libcore net http HttpConnection  lt init gt  HttpConnection java 50  11-13 15 02 52 317  W System err 8012       at libcore net http HttpConnection Address connect HttpConnection java 340  11-13 15 02 52 317  W System err 8012       at libcore net http HttpConnectionPool get HttpConnectionPool java 87  11-13 15 02 52 317  W System err 8012       at libcore net http HttpConnection connect HttpConnection java 128  11-13 15 02 52 317  W System err 8012       at libcore net http HttpEngine openSocketConnection HttpEngine java 316  11-13 15 02 52 317  W System err 8012       at libcore net http HttpEngine connect HttpEngine java 311  11-13 15 02 52 317  W System err 8012       at libcore net http HttpEngine sendSocketRequest HttpEngine java 290  11-13 15 02 52 317  W System err 8012       at libcore net http HttpEngine sendRequest HttpEngine java 240  11-13 15 02 52 317  W System err 8012       at libcore net http HttpURLConnectionImpl getResponse HttpURLConnectionImpl java 282  11-13 15 02 52 317  W System err 8012       at libcore net http HttpURLConnectionImpl getInputStream HttpURLConnectionImpl java 177  11-13 15 02 52 327  W System err 8012       at com abc xyz ContinentActivity getJSONfromURL ContinentActivity java 400  11-13 15 02 52 327  W System err 8012       at com abc xyz ContinentActivity sendContinentQuestions ContinentActivity java 327  11-13 15 02 52 327  W System err 8012       at com abc xyz ContinentActivity access 2 ContinentActivity java 323  11-13 15 02 52 327  W System err 8012       at com abc xyz ContinentActivity LoadQuestions doInBackground ContinentActivity java 254  11-13 15 02 52 327  W System err 8012       at com abc xyz ContinentActivity LoadQuestions doInBackground ContinentActivity java 1  11-13 15 02 52 327  W System err 8012       at android os AsyncTask 2 call AsyncTask java 287  11-13 15 02 52 327  W System err 8012       at java util concurrent FutureTask run FutureTask java 234  11-13 15 02 52 327  W System err 8012       at android os AsyncTask SerialExecutor 1 run AsyncTask java 230  11-13 15 02 52 327  W System err 8012       at java util concurrent ThreadPoolExecutor runWorker ThreadPoolExecutor java 1080  11-13 15 02 52 337  W System err 8012       at java util concurrent ThreadPoolExecutor Worker run ThreadPoolExecutor java 573  11-13 15 02 52 337  W System err 8012       at java lang Thread run Thread java 841  11-13 15 02 52 337  W System err 8012   Caused by  libcore io GaiException  getaddrinfo failed  EAI NODATA  No address associated with hostname  11-13 15 02 52 337  W System err 8012       at libcore io Posix getaddrinfo Native Method  11-13 15 02 52 337  W System err 8012       at libcore io ForwardingOs getaddrinfo ForwardingOs java 61  11-13 15 02 52 337  W System err 8012       at java net InetAddress lookupHostByName InetAddress java 405  11-13 15 02 52 337  W System err 8012           24 more 11-13 15 02 52 337  E log tag 8012   Error parsing data org json JSONException  End of input at character 0 of  11-13 15 02 52 337  W dalvikvm 8012   threadid 194  thread exiting with uncaught exception  group 0x417c1700  11-13 15 02 52 337  E AndroidRuntime 8012   FATAL EXCEPTION  AsyncTask  5 11-13 15 02 52 337  E AndroidRuntime 8012   java lang RuntimeException  An error occured while executing doInBackground   11-13 15 02 52 337  E AndroidRuntime 8012       at android os AsyncTask 3 done AsyncTask java 299  11-13 15 02 52 337  E AndroidRuntime 8012       at java util concurrent FutureTask finishCompletion FutureTask java 352  11-13 15 02 52 337  E AndroidRuntime 8012       at java util concurrent FutureTask setException FutureTask java 219  11-13 15 02 52 337  E AndroidRuntime 8012       at java util concurrent FutureTask run FutureTask java 239  11-13 15 02 52 337  E AndroidRuntime 8012       at android os AsyncTask SerialExecutor 1 run AsyncTask java 230  11-13 15 02 52 337  E AndroidRuntime 8012       at java util concurrent ThreadPoolExecutor runWorker ThreadPoolExecutor java 1080  11-13 15 02 52 337  E AndroidRuntime 8012       at java util concurrent ThreadPoolExecutor Worker run ThreadPoolExecutor java 573  11-13 15 02 52 337  E AndroidRuntime 8012       at java lang Thread run Thread java 841  11-13 15 02 52 337  E AndroidRuntime 8012   Caused by  java lang NullPointerException 11-13 15 02 52 337  E AndroidRuntime 8012       at com abc xyz ContinentActivity sendContinentQuestions ContinentActivity java 328  11-13 15 02 52 337  E AndroidRuntime 8012       at com abc xyz ContinentActivity access 2 ContinentActivity java 323  11-13 15 02 52 337  E AndroidRuntime 8012       at com abc xyz ContinentActivity LoadQuestions doInBackground ContinentActivity java 254  11-13 15 02 52 337  E AndroidRuntime 8012       at com abc xyz ContinentActivity LoadQuestions doInBackground ContinentActivity java 1  11-13 15 02 52 337  E AndroidRuntime 8012       at android os AsyncTask 2 call AsyncTask java 287  11-13 15 02 52 337  E AndroidRuntime 8012       at java util concurrent FutureTask run FutureTask java 234

User · Answer

If reconnecting the WiFi doesn t work for you  try reboot your device   This works for me  Hope it helps

User · Answer

I was testing my application with the Android emulator and I solved this by turning off and turning on the Wi-Fi on the Android emulator device  It worked perfectly

User · Answer

I had the same problem  java net UnknownHostException  Unable to resolve host            I m running Visual Studio 2019 and Xamarin   I also switched back to my WiFi but was on a hot spot   I solved this by clean swiping the emulator   Restore to factory settings   Then re-running visual studio xamarin app which wil redeploy your app again to the fresh emulator   It worked   I thought I was going to battle for days to solve this   Luckily this post pointed me in the right direction   I could not understand how it worked perfectly before and then stopped with no code change   This is my code for reference   using var response   await httpClient GetAsync sb ToString     string apiResponse   await response Content ReadAsStringAsync

User · Answer

I had this issue on Android 10   Changed targetSdkVersion 29 to targetSdkVersion 28 issue resolved  Not sure what is the actual problem   I think not a good practice  but it worked   before   compileSdkVersion 29  minSdkVersion 14  targetSdkVersion 29  Now   compileSdkVersion 29  minSdkVersion 14  targetSdkVersion 28

User · Answer

I had the same problem  but with small difference  I had added NetworkConnectionCallback to check situation when internet connection had changed at runtime  and checking like this before sending all requests   private fun isConnected    Boolean       val activeNetwork   cManager activeNetworkInfo     return activeNetwork    null  amp  amp  activeNetwork isConnected     There can be state like CONNECTING  you can see i  when you turn on wifi  icon starts blinking  after connecting to network  image is static   So  we have two different states  one CONNECT another CONNECTING  and when Retrofit tried to send request internet connection is disabled and it throws UnknownHostException   I forgot to add another type of exception in function which was responsible for sending requests   try    for example  retrofit call   catch  e  Exception            is UnknownHostException - gt   Unknown host           is ConnectException - gt   No internet           else - gt   Unknown exception           It s just a tricky moment that can by related with this problem   Hope  I will help somebody

User · Answer

I encountered this error when running my Android app on my home WiFi  then trying to run it on different WiFi without closing my simulator   Simply closing the simulator and re-launching the app worked for me

User · Answer

I had the same exception in the simulator  Android Studio on OSX  but connecting to the same URL on the iOS simulator worked fine    Looks like it all stemmed from the fact I d be running the simulator whilst connected to a personal hotspot for my internet connection and then came back later while connected to wifi and the simulator didn t like the new internet connection for some reason  seems like it thought the old hotspot was the current connection  which was no longer working    Closing and relaunching the simulator worked

User · Answer

I encountered this problem too  reconnecting the WiFi can solve this   For us  we can check if the phone can resolve the host to IP when we start application  If it cannot resolve  tell the user to check the WiFi and then exit   I hope it helps

User · Answer

Missed to configure tag in manifest file   lt uses-permission android name  android permission ACCESS NETWORK STATE    gt

User · Answer

I was having the same issue  but with Glide  When I was going to disconnect from wifi and reconnect  just like it was suggested here   I noticed that I was in Airplane mode

User · Answer

I got the same error and the issue was that I was on VPN and I didn t realize it  After disconnecting from the VPN and reconnecting to my WIFI network  the problem was resolved

[java] java.net.UnknownHostException: Unable to resolve host "<url>": No address associated with hostname and End of input at character 0 of

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