Helper.java

    public static List<Message> readDocumentsFromFile() {
        final List<Message> empty = new ArrayList<>();
        final Gson gson = new GsonBuilder().create();
        final Type listType = new TypeToken<List<CommonMessage>>() {
        }.getType();
        final File file = new File("/tmp/kznews.json");
        try {
            if (file.exists()) {
                final FileReader fileReader = new FileReader(file);
                final JsonReader reader = new JsonReader(fileReader);
                List<Message> messages = gson.fromJson(reader, listType);
                return messages;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return empty;
    }