Alfonso’s comment:
Finally I got the solution:
// Creates the json object which will manage the information received GsonBuilder builder = new GsonBuilder(); // Register an adapter to manage the date types as long values builder.registerTypeAdapter(Date.class, new JsonDeserializer<Date>() { public Date deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException { return new Date(json.getAsJsonPrimitive().getAsLong()); } }); Gson gson = builder.create();