public void execute() throws Exception {
        Number amount;
        Currency currency;
        String input = "";
        while (true) {
            try {
                input = readAmount(reader);
                amount = Number.valueOf(input);
                currencyDialog.execute("Introduzca la divisa origen: ");
                currency = currencyDialog.getCurrency();
                this.money = new Money(amount, currency);
                break;
            } catch (NumberFormatException ex) {
                throw new Exception(input);
            } catch (IOException ex) {
                System.out.println("An exception has been catched.");
            }
        }
    }