public static <T> T fromJson(String json, Class<T> clazz) { // ... T obj = clazz.newInstance(); for (Field field : clazz.getDeclaredFields()) { field.setAccessible(true); // ... } return obj; } public static String toJson(Object obj) { // ... Class<?> clazz = obj.getClass(); for (Field field : clazz.getDeclaredFields()) { field.setAccessible(true); // ... } return json; }