gistfile1.java

    /**
     * Charges annual fee on all accounts if an annual fee is applicable. Returns
     * total amount of revenue collected by summing the rates of all annual fees charged
     * 
     * @return Sum of annual fees charged
     */
    public int chargeAnnualFees()
    {
        int totalAnnualFees = 0;
        for (Account account : accounts)
        {
            if (account instanceof AnnualAcct || account instanceof CreditCard)
            {
                AnnualAcct accountWithAnnualFee = (AnnualAcct) account;
                accountWithAnnualFee.chargeFee();
                totalAnnualFees += accountWithAnnualFee.annualFee();
            }
        }
        return totalAnnualFees;
    }