Ggtcf

I want to get the first "City" object from this JSON response from a URL (or get them all as an array and then use .map() operator in RxJava to get the first city):

 totalResultsCount: 5,
 names: [
 
 city: stockholm
 ,
 
 city: oslo
 ,
 
 city: london
 ,
 
 city: moscow
 ,
 
 city: mumbai
 
 ]

Here is code responsible for getting this:

public interface MyApi 

 @GET("searchJSON?")
 Observable<City[]> getPopulation(
 @QueryMap Map<String, String> queries
 );

and this class

public class MyApiService

 private final String baseUrl = "myapiurl";
 private MyApi api;
 private final Gson gson;
 private final OkHttpClient okHttpClient;

 public MyApiService()
 gson = new Gson();
 HttpLoggingInterceptor httpLoggingInterceptor = new HttpLoggingInterceptor();
 httpLoggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BASIC);
 okHttpClient = new OkHttpClient();
 okHttpClient.newBuilder().addInterceptor(httpLoggingInterceptor);
 buildApi();
 

 private void buildApi()
 api = new Retrofit.Builder()
 .baseUrl(baseUrl)
 .client(okHttpClient)
 .addConverterFactory(GsonConverterFactory.create(gson))
 .addCallAdapterFactory(RxJava2CallAdapterFactory.create())
 .build()
 .create(MyApi.class);
 

 public Observable<City> getPopulation(String city) 
 return api
 .getPopulation(city)
 .map(c -> c[0])
 .subscribeOn(Schedulers.io());
 

When I call getPopulation from an activity, I get this message:

D/Response: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column
2 path $

Here is how my City class looks like:

public class City 

 @SerializedName("city")
 private String name;

 public City(String name) 
 this.name = name;
 

Any ideas?

EDIT:

I tried adding a custom deserializer like:

public class MyDeserializer implements JsonDeserializer<City> 

 @Override
 public City deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException 
 JsonElement cities = json.getAsJsonObject().get("names");
 return new Gson().fromJson(cities, City.class);
 

and changing to:

gson = new GsonBuilder()
 .registerTypeAdapter(City.class, new MyDeserializer())
 .create();

but I still get the exact same response as earlier.

Your custom deserializer uses getAsJsonObject("names") but names is a JsonArray in your json response.

names: [] // This is a JsonArray

names: // This is a JsonObject

I manage to solve this.

I changed my API calls to:

@GET("searchJSON?")
 Observable<ResponseBody> getPopulation(
 @QueryMap Map<String, String> queries
 );

And I changed my api call method to:

public Observable<City> getPopulation(String city) {
 return api
 .getPopulation(city)
 .map(c -> c.getCities().get(0))
 .subscribeOn(Schedulers.io());

And I changed my Serializeble POJOs to:

public class ResponseBody implements Serializable


 @SerializedName("totalResultsCount")
 @Expose
 private int totalResultsCount;
 @SerializedName("names")
 @Expose
 private List<City> cities = null;

 public ResponseBody() 
 

 public ResponseBody(int totalResultsCount, List<City> cities) 
 super();
 this.totalResultsCount = totalResultsCount;
 this.cities = cities;
 

 public int getTotalResultsCount() 
 return totalResultsCount;
 

 public void setTotalResultsCount(int totalResultsCount) 
 this.totalResultsCount = totalResultsCount;
 

 public List<City> getCities() 
 return cities;
 

 public void setNames(List<City> cities) 
 this.cities = cities;
 

and

public class City implements Serializable

 @SerializedName("name")
 @Expose
 private String name;

 public City() 
 

 public City(String name) 
 super();
 this.name = name;
 

 public String getName() 
 return name;
 

 public void setName(String name) 
 this.name = name;
 

And I complete removed the custom Deserializer.

It was a combination of my POJO and Wrong choice of RxJava operations which led to my problem. I hope this answer might help someone in the future.

If anyone have a better solution/way to handle this I would appreciate comments.