Null-pointer Exception, Retrofit?

Question

I am trying to get an id from URL but getting the null pointer exception

java.lang.NullPointerException: Attempt to read from field 'java.lang.String com.hex.encode.ID_Model$User.id' on a null object reference at com.hex.encode.Home$3.onResponse(Home.java:99)

and this is the code I am using to get the id:

private void GetID() {
        Call<ID_Model> idcall = fetchdata.getIdService().getID(user_search);
        idcall.enqueue(new Callback<ID_Model>() {
            @Override
            public void onResponse(@NonNull Call<ID_Model> call,@NonNull Response<ID_Model> response) {
                assert response.body() != null;
                String fetched_id =response.body().getUser().getId;//this is where the exception is poping
                GetData(fetched_id);
            }

            @Override
            public void onFailure(@NonNull Call<ID_Model> call, @NonNull Throwable t) {
                //something//
            }
        });
    }

and below is the fetchdata class:

class fetchdata {
    private static UserFetchData userdatafetch = null;
    private static UserIDFetch fetchService = null;

    static  UserIDFetch getIdService() {
        if (fetchService == null) {
            String id_url = "url_and_it's_working";
            Retrofit fetch_id = new Retrofit.Builder()
                    .baseUrl(id_url)
                    .addConverterFactory(GsonConverterFactory.create())
                    .build();
            fetchService = fetch_id.create(UserIDFetch.class);
        }
        return fetchService;
    }

    public interface UserIDFetch{
        @GET("{user_input}"+"/")
        Call<ID_Model> getID(@Path("user_input") String s);
    }
}

Edit

Here is the Id_Model :

public class ID_Model {

    @SerializedName("user")
    @Expose
    public User user;

    public User getUser() {
        return user;
    }

    public class User {

        @SerializedName("id")
        @Expose
        public String id;

        public String getId() {
            return id;
        }
        public void setId(String id) {
            this.id = id;
        }

    }
}

Edit Here is the response from the API Server : https://justpaste.it/4gk8r

`ID_Model` will be null if retrofit failed to parse the html body into your object. Show the raw url response and your model class, please — OneCricketeer, Jul 25 '18 at 13:18
hii @cricket_007 i've posted the ID_MODEL class in the main question please take a look. — wiils, Jul 25 '18 at 13:48
@WeslleyBarbosa check i have used OnResponce callback so the response is successfull there is somethingin the ID_Model. I have update question with it. — wiils, Jul 25 '18 at 13:54
Always you receive response, but, response code can be 200(OK), 400(BAD REQUEST) — Weslley Barbosa, Jul 25 '18 at 14:15
Please show the html response as well for the url your application is reading from — OneCricketeer, Jul 25 '18 at 14:15
@cricket_007 I've posted the responce from the server in the main question please follow the link to view it. Thank You — wiils, Jul 25 '18 at 14:29

score 2 · Answer 1 · edited Aug 21 '18 at 05:57

You need to check response is successful with response.isSucessful(). And it also depends on server side they send the 200 when API successfully hit on server and then we need to check the API response is it success or failure on the basis of the response.

In your case, I think API call is success with 200 and return some response but response.body().getUser() is null. So you have to check the response of API.

OneCricketeer · Answer 2 · 2018-07-25T14:52:15.743

2

Your response looks like this

{
   ... 
  "graphql": {
     "user": {
       ... 
      "id": "1067259270",

Which means you have forgot to parse the graphql key as well as every other key, therefore the user is null.

At an absolute minimum you need a model like this.

class ResponseModel {
    GraphQLModel graphql;

    class GraphQLModel {
        UserModel user;

        class UserModel {
            int id;
        } 
    } 
}

My suggestion would be to use an actual GraphQL library rather than Retrofit and generate your model using apollo-codegen (if you use Apollo Client)

edited Jul 25 '18 at 14:52

answered Jul 25 '18 at 14:38

OneCricketeer

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Yes just found that, how can i update the current ID_MODEL for this ? – wiils Jul 25 '18 at 14:40
I would use `apollo-codegen` project to create every GraphQL model for you rather than changing your model by hand – OneCricketeer Jul 25 '18 at 14:46

Null-pointer Exception, Retrofit?

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