OkHttp / Retrofit / Gson: Expected BEGIN_OBJECT but was BEGIN_ARRAY

Question

I am having this

Error: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2 path $

while trying to retreive data from an API. I am using Retrofit, Gson and OkHttpClient. I am trying to display data from characters (API: http://hp-api.herokuapp.com/api/characters/house/gryffindor) into a RecyclerView.

This is my code, I hope you can find with any clue of what's happening:

private void lanzarPeticion(String house) {
    loggingInterceptor = new HttpLoggingInterceptor().setLevel(HttpLoggingInterceptor.Level.BODY);
    httpClientBuilder = new OkHttpClient.Builder().addInterceptor(loggingInterceptor);

    retrofit = new Retrofit.Builder().baseUrl("http://hp-api.herokuapp.com/api/")
            .addConverterFactory(GsonConverterFactory.create())
            .client(httpClientBuilder.build())
            .build();

    WebServiceClient client = retrofit.create(WebServiceClient.class);

    Call<Data> call = client.getPersonajes(house);
    call.enqueue(new Callback<Data>() {
        @Override
        public void onResponse(Call<Data> call, Response<Data> response) {
            adapter.setPersonajes(response.body().getResults());
        }

        @Override
        public void onFailure(Call<Data> call, Throwable t) {
            Log.d("TAG1", "Error: " + t.getMessage());
        }
    });
}

My WebServiceClient:

public interface WebServiceClient {
    @GET("characters/house/{house}")
    Call<Data> getPersonajes(@Path("house") String house);

    @GET()
    Call<Personaje> getPersonaje(@Url String url);
}

This is my Data class (for the getResults())

public class Data {
    private String count;
    private String next;
    private List<Personaje> results;

    public String getCount() {
        return count;
    }

    public void setCount(String count) {
        this.count = count;
    }

    public String getNext() {
        return next;
    }

    public void setNext(String next) {
        this.next = next;
    }

    public List<Personaje> getResults() {
        return results;
    }

    public void setResults(List<Personaje> results) {
        this.results = results;
    }
}

See also [java.lang.IllegalStateException: Expected BEGIN\_OBJECT but was BEGIN\_ARRAY Kotlin](https://stackoverflow.com/questions/58358594/java-lang-illegalstateexception-expected-begin-object-but-was-begin-array-kotli) — Codebling, Jun 07 '21 at 22:54

Anand · Accepted Answer · 2021-06-07T22:49:14.677

Error: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 2 path $

As the error clearly says, you are trying to parse JSONArray into a JSONObject

@GET("characters/house/{house}")
Call<Data> getPersonajes(@Path("house") String house);

This service method expecting JSONObject, but according the logcat shared by in the image, the response is giving JSONArray. Instead you should parse it as:

@GET("characters/house/{house}")
Call<List<Personaje>> getPersonajes(@Path("house") String house)

Codebling · Answer 2 · 2021-06-07T22:51:07.667

There doesn't seem to be a good reason to use your Data class here (the fact that the class is very generically called "Data" seems to reflect that). You're receiving multiple Personaje, so you should accept multiple Personaje:

    Call<List<Personaje>> getPersonajes(@Path("house") String house);

If you use the Data class, (without List), deserializer will expect a single Object, hence the error (Expected BEGIN_OBJECT). You might be able to get it to work if you implement List in Data, but it seems like code for nothing when Call<List<Personaje>> getPersonajes should work fine.

OkHttp / Retrofit / Gson: Expected BEGIN_OBJECT but was BEGIN_ARRAY

2 Answers2