systemDataModel.setFreeMemory(20); systemDataModel.setCpuUsedPercentage(20); List<SystemDataModel> lists = Lists.newArrayList(); lists.add(systemDataModel); lists.add(systemDataModel); Gson gson = new Gson(); String json = gson.toJson(lists); ArrayList<SystemDataModel> fromJson = gson.fromJson(json, getTypeToken()); System.out.println(fromJson.get(0).getClass()); } private Type getTypeToken() { return new TypeToken<ArrayList<SystemDataModel>>() { private static final long serialVersionUID = 1L; }.getType(); } }