Android JSON parsing Retrofit

Question

I'm new to Retrofit and JSON and I don't really know how to parse the next json string:

{
"weight":[
    {   "bmi":21,
        "date":"2016-12-09",
        "fat":14.059000015258789,
        "logId":1222222222222,
        "source":"Aria",
        "time":"11:58:24",
        "weight":68
    },
    {   "bmi":21.83,
        "date":"2016-12-14",
        "logId":1222222222223,
        "source":"Aria",
        "time":"14:31:39",
        "weight":70.7
    }
]

}

I just want "weight" and "date" inside weight array. I've created a pojo class following some examples but it's not working. Also when trying it with my pojo class I couldn't get "weight" as a string (I'll then use it as a double) using .string().

(I know using .toString() shows something like "com.myPackage.MyPojo@xxxx").

For now, I have only been able to get the whole json through ResponseBody:

Call<ResponseBody>call = repository.getFitbitApi().getData();
               call.enqueue(new Callback<ResponseBody>() {
                   @Override
                   public void onResponse(Call<ResponseBody> call, retrofit2.Response<ResponseBody> response) {
                       try {
                           System.out.println(response.body().string());
                       } catch (IOException e) {
                           e.printStackTrace();
                       }
                   }

                   @Override
                   public void onFailure(Call<ResponseBody> call, Throwable t) {

                   }
               });

What am I doing wrong? Here are my pojo classes, just an attempt...:

public class WeightList {

@SerializedName("weight")
@Expose

private ArrayList<WeightLogFitbit> weight = new ArrayList<>();

public WeightList(){

}

public ArrayList<WeightLogFitbit> getWeight() {
    return weight;
}


public void setWeight(ArrayList<WeightLogFitbit> weight) {
    this.weight = weight;
}

} And:

public class WeightLogFitbit {

//Variables in my JSON
@SerializedName("bmi")
@Expose
private String bmi;

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

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

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

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

@SerializedName("weight")
@Expose
private double weight;

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

public WeightLogFitbit(){}

//Getters and setters
public double getWeight() {
    return weight;
}

public void setWeight(double weight) {
    this.weight = weight;
}

public String getDate() {
    return date;
}
public void setDate(String date) {
    this.date = date;
}

public String getSource() {
    return source;
}
public void setSource(String source) {
    this.source = source;
}

public String getBmi(){
    return bmi;
}
public void setBmi(String bmi) {
        this.bmi = bmi;
    }

//
public String getFat(){
    return fat;
}
public void setFat(String fat) {
    this.fat = fat;
}


public String getTime() {
    return time;
}
    public void setTime(String time) {
        this.time = time;
    }
public String getLogId() {
    return logId;
}
public void setLogId(String logId) {
        this.logId = logId;
}

}

NOTE: I'm using RxSocialConnect library, which implements RxJava, Retrofit 2, OkHttp3 and gson, just in case. I did this following this example.

Rest of classes I'm using:

public class FitbitBtnActivity extends AppCompatActivity {

private FitbitRepository repository;

    @Override protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_fitbit_btn);

        repository = new FitbitRepository();

        setUpFitbit();

    }


private void setUpFitbit() {
    findViewById(R.id.fitbitbtn).setOnClickListener(v ->
            RxSocialConnect.with(this, repository.fitbitService())
                    .subscribe(response -> response.targetUI().showToken(response.token()),
                            error -> showError(error))
    );

    findViewById(R.id.retrievebtn).setOnClickListener(v -> {
    Call<ResponseBody>call = repository.getFitbitApi().getData();
               call.enqueue(new Callback<ResponseBody>() {
                   @Override
                   public void onResponse(Call<ResponseBody> call, retrofit2.Response<ResponseBody> response) {
                       try {
                           System.out.println(response.body().string());
                       } catch (IOException e) {
                           e.printStackTrace();
                       }
                   }

                   @Override
                   public void onFailure(Call<ResponseBody> call, Throwable t) {

                   }
               });

                //Original code from example in RxSocialConnect

                       /*.subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe(new Action1<Object>() {
                               @Override
                               public void call(Object user) {
                                   FitbitBtnActivity.this.showUserProfile(user.toString());
                               }
                           },
                        error -> FitbitBtnActivity.this.showError(error));*/

    }
    );
}

And:

public class FitbitRepository {


private final FitbitApiRest fitbitApi;

public FitbitRepository() {
    fitbitApi = initFitbitApiRest();
}

private FitbitApiRest initFitbitApiRest() {
    OkHttpClient client = new OkHttpClient.Builder()
            .addInterceptor(new OAuth2Interceptor(FitbitApi20.class))
            .build();

    return new Retrofit.Builder()
            .baseUrl(FitbitApiRest.URL_BASE)
            .client(client)
            .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
            .addConverterFactory(GsonConverterFactory.create())
            .build().create(FitbitApiRest.class);
}



FitbitApiRest getFitbitApi() {
    return fitbitApi;
}



interface FitbitApiRest {
    String URL_BASE = "https://api.fitbit.com";

    @GET("myrequest.json")
    Call<ResponseBody> getData();
}

OAuth20Service fitbitService() {


    final String client_id = "xxxxx";
    final String client_secret = "1xxxxxxxxxxxxxxxxxx";
    final String redirect_uri = "http://example.com";
    final String permissions = "weight";

    return new ServiceBuilder()
            .apiKey(client_id)
            .apiSecret(client_secret)
            .callback(redirect_uri)
            .scope(permissions)
            .build(FitbitApi20.instance());
}

}

Answer 1

You need to add this to your dependencies:

compile 'com.squareup.retrofit2:converter-gson:your-version'

and then add a gson converter to your Retrofit instance like this:

Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://api.example.com")
.addConverterFactory(GsonConverterFactory.create())
.build();

and change your call in the api to return WeightList:

Call<WeightList> getData();