[FIXED] Response body always null in android from retrofit2 api request

Issue

I'm developing an android app with android studio, and I have a rest api, which I developed with spring. And every time I use retrofit to retrieve something from the server I get null body. Even though my server sends the data.

I've tried ScalarsConverterFactory and GsonConverterFactory, I tried as well changing the type of my Call to String, to ResponseBody and to JsonObject

here I make the call:

Retrofit retrofit = new Retrofit.Builder()
                .addConverterFactory(GsonConverterFactory.create())
                .baseUrl("my_url")
                .build();

ServerService service = retrofit.create(ServerService.class);
Call<List<String>> call = service.getUserAlbums("addcookie");
Response<List<String>> response = call.execute();

ServerService.java

@GET("/cmu/getUserAlbums")
Call<List<String>> getUserAlbums(@Header("Cookie") String cookie);

Here is the code in the server

@RequestMapping(value = "/getUserAlbums", method = RequestMethod.GET)
    @ResponseStatus(HttpStatus.FOUND)
    public List<String> getUserAlbums() {
        Authentication auth = SecurityContextHolder.getContext().getAuthentication();
        User user = userService.getUserByUsername(auth.getName());
        return userService.getUserByUsername(user.getUsername()).getAlbums();

    }

I was expecting to get a list as a string, I get the HTTP code 302, and in my console I can see that the server returns the List, but I can't receive on android.

Solution

I fixed the issue, basically retrofit considers a response successful if the code is between 200 - 299, so as it was returning the 302, the response body I was looking for was in .errorBody().

Answered By - Mihail
Answer Checked By - Katrina (JavaFixing Volunteer)