@Override
 public List<Transaction> getAllTransaction(String accNumber, long startTime, long stopTime) {
   List<Transaction> transactionList =
       transactionDAO.getAllTransaction(accNumber, startTime, stopTime);
   if (transactionList == null) return null;
   else return transactionList;
 }
 @Override
 public List<Transaction> getAllTransaction(String accNumber, int number) {
   List<Transaction> transactionList = transactionDAO.getAllTransaction(accNumber, number);
   if (transactionList == null) return null;
   else return transactionList;
 }