public MacAddress findMacWithIp(String macStr, String ipStr) {
   // TODO Auto-generated method stub
   for (MacAddress mac : getListMacs()) {
     if (mac.getMacAddress().equals(macStr)) {
       for (IpAddress ip : mac.getAllIpAddress()) {
         if (ip.getIpAddress().equals(ipStr)) {
           return mac;
         }
       }
     }
   }
   return null;
 }
 private String getLastEndTimeForDay() {
   // TODO Auto-generated method stub
   if (getListMacs().size() > 0) {
     String endTime = "00:00";
     for (MacAddress mac : getListMacs()) {
       for (IpAddress ip : mac.getAllIpAddress()) {
         String ipEndTime = ip.getEndTime();
         if (ipEndTime.compareTo(endTime) > 0) {
           endTime = ipEndTime;
         }
       } // end for
     } // end for
     return endTime;
   }
   return null;
 }