Retrofit 2 simple upload file to server

i'm newbie in retrofit and in this code i want to upload file as an image or other format to server, i read Retrofit document about that, but i can't do that,

i can create provider and i can use that to POST or GET from server, but my problem is for that is upload file.

Thanks to advance

My SignalProvider class:

public class SignalProvider { private SignalRetrofitServiceProviders signalRetrofitServiceProviders; public SignalProvider(){ OkHttpClient httpClient = new OkHttpClient(); Retrofit retrofit = new Retrofit.Builder() .baseUrl(ClientSettings.SignalWebBaseUrl) .client(httpClient) .addConverterFactory(GsonConverterFactory.create()) .build(); signalRetrofitServiceProviders = retrofit.create(SignalRetrofitServiceProviders.class); } public SignalRetrofitServiceProviders getServices(){ return signalRetrofitServiceProviders; } } 

My SignalRetrofitServiceProviders class:

public interface SignalRetrofitServiceProviders { @POST("storeLists") Call<List<StoreLists>> getStoreLists(); @Multipart @POST("upload/newVitrine/{userId}") Call<ResponseBody> uploadImageToServer( @Path("id") int id, @Part("description") RequestBody description, @Part MultipartBody.Part file); } 

and then Upload file method:

private void uploadFile() { // create upload service client SignalProvider signalProvider = new SignalProvider(); SignalRetrofitServiceProviders service = signalProvider.getServices(); File file = new File(Application.IMAGES + "/" + "test_image.jpg"); RequestBody requestFile = RequestBody.create(MediaType.parse("multipart/form-data"), file); MultipartBody.Part body = MultipartBody.Part.createFormData("picture", file.getName(), requestFile); String descriptionString = "hello, this is description speaking"; RequestBody description = RequestBody.create( MediaType.parse("multipart/form-data"), descriptionString); Call<ResponseBody> call = service.uploadImageToServer("1",description, body); call.enqueue(new Callback<ResponseBody>() { @Override public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) { Log.e("Upload", "success"); } @Override public void onFailure(Call<ResponseBody> call, Throwable t) { Log.e("Upload error:", t.getMessage()); } }); } 

I get this error:

 Error:(112, 42) error: method uploadImageToServer in interface SignalRetrofitServiceProviders cannot be applied to given types; required: int,com.squareup.okhttp.RequestBody,Part found: int,okhttp3.RequestBody,Part reason: actual argument okhttp3.RequestBody cannot be converted to com.squareup.okhttp.RequestBody by method invocation conversion