private List<DateTime> getSortedArriveDateTimeList(List<ContainerData> containers) {
        // Create 
        List<DateTime> dateTimes = new ArrayList();
        
        // Find all unique DateTimes
        for(ContainerData container : containers) {
            DateTime dateTime = container.getEnterDateTimeFrom();
            boolean found = false;
            int len = dateTimes.size();
            for(int i = 0; i < len; i++) {
                if (dateTimes.get(i).compareTo(dateTime) == 0) {
                    found = true;
                    break;
                }
            }
            if (!found) {
                dateTimes.add(dateTime);
            }
        }
        
        // Sort the list
        Collections.sort(dateTimes);
        
        // Return the result
        return dateTimes;
    }