public static Map<String, Map<String, List<Activity> listToMap(
      List<Activity> activities) {
    Map<String, Map<String, List<Activity> map = new HashMap<String, Map<String, List<Activity>();
    for (Activity detail : activities) {
      if (!map.containsKey(detail.getActivityCode())) {
        Map<String, List<Activity mapValue = new HashMap<String, List<Activity();
        List<Activity> listValue = new ArrayList<Activity>();
        listValue.add(detail);
        mapValue.put(detail.getActivityVersion(), listValue);
        map.put(detail.getActivityCode(), mapValue);
      } else {
        Map<String, List<Activity mapValue = map.get(detail
            .getActivityCode());
        if (!mapValue.containsKey(detail.getActivityVersion())) {
          List<Activity> listValue = new ArrayList<Activity>();
          listValue.add(detail);
          mapValue.put(detail.getActivityVersion(), listValue);
        } else {
          List<Activity> mapValueList = mapValue.get(detail
              .getActivityVersion());
          mapValueList.add(detail);
          mapValue.put(detail.getActivityVersion(), mapValueList);
        }
      }
    }
    return map;
  }