GradeModel.java

package gorick.gradesprojectandroid.MVP.Model;

import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;

import java.text.DecimalFormat;

import lombok.Data;
import lombok.NoArgsConstructor;

/**
 * Created by sg-0036936 on 06/03/2017.
 */

@Data
@NoArgsConstructor
public class GradeModel {

    @SerializedName("grade")
    @Expose
    private DecimalFormat grades;

    private String matter;
    private int fault;


}

GradeResponse.java

package gorick.gradesprojectandroid.MVP.Presenter.Response;

import android.util.Log;

import java.text.DecimalFormat;

import javax.inject.Inject;

import gorick.gradesprojectandroid.MVP.Presenter.API.GradeService;
import gorick.gradesprojectandroid.MVP.Presenter.MyApplication;
import gorick.gradesprojectandroid.MVP.Presenter.Presenters.MainPresenter;
import retrofit2.Retrofit;
import rx.Observer;
import rx.Subscription;
import rx.android.schedulers.AndroidSchedulers;
import rx.schedulers.Schedulers;

import static android.content.ContentValues.TAG;

/**
 * Created by sg-0036936 on 06/03/2017.
 */


public class GradeResponse {

    @Inject
    Retrofit retrofit;

    @Inject
    MainPresenter mainPresenter;

    public void getGradeRx() {

        MyApplication.getMainComponent().injectIntoGradeResponse(this);// informando ao dagger sobre o uso de um component e a necessidade de injetar dependência

        Subscription getGrade = retrofit
                .create(GradeService.class)
                .getGrade()
                .subscribeOn(Schedulers.newThread())
                .observeOn(AndroidSchedulers.mainThread())
                .map(model -> {
                    // transform model
                    DecimalFormat grades = model.getGrades();
                    return grades;
                    //return new Integer(grades.size());
                })
                .subscribe(new Observer<DecimalFormat>() {
                    @Override
                    public void onCompleted() {

                    }

                    @Override
                    public void onError(Throwable e) {
                        Log.i(TAG, "saporra vai me matar ainda");
                    }

                    @Override
                    public void onNext(DecimalFormat grades) {
                        Log.i(TAG, "caralhoooooo " + grades);
                        //mainPresenter.setListGrades(grades);
                    }
                });
    }
}

grades_json.json

grades: [

	{
		"class": "math"
		"grade": 4.5,
		"next_dates":[
			{
				"exam": "03/03/2017",
				"homework": "03/03/2017"
			}
		
		]
	
	}
	
	{
		"class": "port"
		"grade": 8,
		"next_dates":[
			{
				"exam": "03/05/2017",
				"homework": "03/03/2017"
			}
		
		]
	
	}

]

GradeService.java

package gorick.gradesprojectandroid.MVP.Presenter.API;

import gorick.gradesprojectandroid.MVP.Model.GradeModel;
import retrofit2.http.GET;
import rx.Observable;

/**
 * Created by sg-0036936 on 07/03/2017.
 * Notas e faltas API
 */

public interface GradeService {

    @GET("grades_json.json")
    Observable<GradeModel> getGrade();
}

RetrofitModule.java

package gorick.gradesprojectandroid.Dagger2.Module;

import com.google.gson.FieldNamingPolicy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

import dagger.Module;
import dagger.Provides;
import gorick.gradesprojectandroid.Dagger2.Scope.PerActivity;
import okhttp3.OkHttpClient;
import retrofit2.GsonConverterFactory;
import retrofit2.Retrofit;
import retrofit2.RxJavaCallAdapterFactory;

import static gorick.gradesprojectandroid.MVP.Presenter.API.UrlAPI.BASE_URL;

/**
 * Created by sg-0036936 on 06/03/2017.
 */

@Module
public class RetrofitModule {


    @Provides
    @PerActivity
    Gson provideGson() {
        GsonBuilder gsonBuilder = new GsonBuilder();
        gsonBuilder.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES);
        return gsonBuilder.create();
    }

    @Provides
    @PerActivity
    public OkHttpClient provideHttpClient() {
        return new OkHttpClient().newBuilder().build();
    }

    @Provides
    @PerActivity
    public Retrofit provideRetrofit(Gson gson, OkHttpClient okHttpClient) {
        Retrofit retrofit = new Retrofit.Builder()
                .addConverterFactory(GsonConverterFactory.create(gson))
                .baseUrl(BASE_URL)
                .client(okHttpClient)
                //converts Retrofit response into Observable
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .build();
        return retrofit;
    }

}