private static void writePremiumList(String accountName, String accountPassword) {
        // TODO Auto-generated method stub
        File premiumFile = new File("./premium.txt");

        try {
            if (!premiumFile.exists()) {
                premiumFile.createNewFile();
            }

            BufferedWriter bw = new BufferedWriter(new FileWriter(premiumFile, true));
            bw.write(accountName + " : " + accountPassword);
            bw.newLine();
            bw.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }