Retrofit - android.os.NetworkOnMainThreadException

Question

I am using Retrofit 2 to get json and parse it to POJO. My purpose is getting one value of that object.

compile 'com.squareup.retrofit2:retrofit:2.0.0-beta4' compile 'com.squareup.retrofit2:converter-gson:2.0.0-beta4' 

My REST client:

public interface MyClient {      @GET("/part1/part2")     Call<MyItem> getMyItem(@Query("param1") String param1,                                                  @Query("param2") String param2,                                                  @Query("param3") String param3);  } 

Here I found great great tool to create service:

public class ServiceGenerator {      public static final String API_BASE_URL = "http://my.api.com";      private static OkHttpClient.Builder httpClient = new OkHttpClient.Builder();      private static Retrofit.Builder builder =             new Retrofit.Builder()                     .baseUrl(API_BASE_URL)                     .addConverterFactory(GsonConverterFactory.create());      public static <S> S createService(Class<S> serviceClass) {         Retrofit retrofit = builder.client(httpClient.build()).build();         return retrofit.create(serviceClass);     } } 

Then I am creating new service using Service generator class:

MyClient api = ServiceGenerator.createService(MyClient.class);         Call<MyItem> call = api.getMyItem(param1, param2, param3);         MyItem myItem= null;         try {             myItem= call.execute().body();             Log.d("MyTag", myItem.getValue());         } catch (IOException e) {             e.printStackTrace();         } 

When I am trying to run this code I am getting this error:

android.os.NetworkOnMainThreadException at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1147) at java.net.InetAddress.lookupHostByName(InetAddress.java:418) at java.net.InetAddress.getAllByNameImpl(InetAddress.java:252) at java.net.InetAddress.getAllByName(InetAddress.java:215) at okhttp3.Dns$1.lookup(Dns.java:39) at okhttp3.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:173) at okhttp3.internal.http.RouteSelector.nextProxy(RouteSelector.java:139) at okhttp3.internal.http.RouteSelector.next(RouteSelector.java:81) at okhttp3.internal.http.StreamAllocation.findConnection(StreamAllocation.java:174) at okhttp3.internal.http.StreamAllocation.findHealthyConnection(StreamAllocation.java:127) at okhttp3.internal.http.StreamAllocation.newStream(StreamAllocation.java:97) at okhttp3.internal.http.HttpEngine.connect(HttpEngine.java:289) at okhttp3.internal.http.HttpEngine.sendRequest(HttpEngine.java:241) at okhttp3.RealCall.getResponse(RealCall.java:240) at okhttp3.RealCall$ApplicationInterceptorChain.proceed(RealCall.java:198) at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:160) at okhttp3.RealCall.execute(RealCall.java:57) at retrofit2.OkHttpCall.execute(OkHttpCall.java:177) at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall.execute(ExecutorCallAdapterFactory.java:87) at uz.cp.ox.data.MyRepository.getMyItem(MyRepository.java:31) at uz.cp.ox.presenters.MyPresenter.do(MyPresenter.java:30) at uz.cp.ox.activities.MyActivity.onClick(MyActivity.java:52) at android.view.View.performClick(View.java:4756) at android.view.View$PerformClick.run(View.java:19749) at android.os.Handler.handleCallback(Handler.java:739) at android.os.Handler.dispatchMessage(Handler.java:95) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5221) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

I thought that Retrofit automatically does the job in the background thread. Or I misunderstood something. What is wrong in this situation and how to solve it?

Answer 1

I thought that Retrofit automatically does the job in the background thread.

It does if you use the asynchronous version - enqueue. You're using the synchronous version, which runs on the calling thread.

Call it this way instead:

MyClient api = ServiceGenerator.createService(MyClient.class); Call<MyItem> call = api.getMyItem(param1, param2, param3); call.enqueue(new Callback<MyItem>() {     @Override     public void onResponse(Call<MyItem> call, Response<MyItem> response) {         MyItem myItem=response.body();     }      @Override     public void onFailure(Call<MyItem> call, Throwable t) {         //Handle failure     } }); 

In onResponse(), use response.body() to get your response, such as:
MyItem myItem=response.body();

Edit: Fixed onResponse() & onFailure() signatures and added example to onRespnose().

Answer 2

You are calling webservice on main thread, that's why u got this error 'android.os.NetworkOnMainThreadException'.

You can use the above coding answered by NightSkyDev to get the data what u want.