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

Question

I have created an application that loads a question from my web services, and it works fine for me. 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 for some time and crashes all of a sudden 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;

}

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

Reconnecting to wifi might help to solve this.

For us, we can check if the phone can resolve the host to IP when we start the application. If it cannot resolve, tell the user to check the WiFi and then exit.

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Answer 2

In this case, you are advised to check whether the phone can resolve the host to an IP address when the application starts. If the resolution fails, you can check your  WiFi connection before the application exits. Also rebooting your system might help.