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 < json.length(); i++) {                 HashMap<String, String> map = new HashMap<String, String>();                 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; } 

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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.<init>(HttpConnection.java:70) 11-13 15:02:52.317: W/System.err(8012):     at libcore.net.http.HttpConnection.<init>(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) 

Answer 1

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.

Answer 2

If reconnecting the WiFi doesn't work for you, try reboot your device.

This works for me. Hope it helps.