Upload Multiple Images Using Retrofit

ApiService.java

// Example url :- money_expenses and response model - ServerResponse (your response success model)

    @POST("money_expense")
    Call<ServerResponse> createExpenses(@Body RequestBody files);

Presenters.java

// Your Presenter Class

    public void postMoneyExpenses(RequestBody files) {

        ApiService apiService = ApiClient.getClient().create(ApiService.class);

        apiService.createExpenses(files).enqueue(new Callback<ServerResponse>() {
            @Override
            public void onResponse(@NonNull Call<ServerResponse> call, @NonNull Response<ServerResponse> response) {

                if (response.isSuccessful()) {

                    try {
                        assert response.body() != null;
                        getView().onSuccess(response.body().getMessage());


                    } catch (Exception e) {
                        e.printStackTrace();
                    }

                } else {
                    getView().onFailure(response.message());
                }

            }

            @Override
            public void onFailure(@NonNull Call<ServerResponse> call, @NonNull Throwable throwable) {
                super.onFailure(call, throwable);
                getView().onFailure(super.getCause());


            }
        });

    }

UtilitiesFunctions.java

// place this code in your utitlies class
// will help in future projects
// See how other paramters can be added in multiparts
// here doc[] is the multiple image key and other are just fields. ;)
// ArrayList<Uri> images is the list of images you get from onResult

    public static MultipartBody getAddReportFiles(Context context, ArrayList<Uri> images, String amount, String topicId, String description) {

        MultipartBody.Builder builder = new MultipartBody.Builder();
        builder.setType(MultipartBody.FORM);
        builder.addFormDataPart("amount", amount);
        builder.addFormDataPart("topic_id", topicId);
        builder.addFormDataPart("description", description);

        for (int i = 0; i < images.size(); i++) {
            File file = new File(getRealPathFromUri(context, Uri.parse(String.valueOf(images.get(i)))));
            builder.addFormDataPart("doc[]", file.getName(), RequestBody.create(MediaType.parse("multipart/form-data"), file));
        }
        return builder.build();
    }

    public static String getRealPathFromUri(Context context, Uri contentUri) {
        Cursor cursor = null;
        try {
            String[] proj = {MediaStore.Images.Media.DATA};
            cursor = context.getContentResolver().query(contentUri, proj, null, null, null);
            int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
            cursor.moveToFirst();
            return cursor.getString(column_index);
        } finally {
            if (cursor != null) {
                cursor.close();
            }
        }
    }

YourActivity.java

// Call from your Activity/ Fragments

presenter.createExpensesBill(UtilitiesFunctions.getAddReportFiles(CreateExpenses.this,addedImagePaths,totalExpensesAmount,String.valueOf(spinnerExpensesTopic.getSelectedView().getTag()),expensesDescriptions));


// DONE !
// Tips
// Use FishBun image picker library , easy to use