小编use*_*240的帖子

我想运行一个程序,可以根据输入的数字确定信用卡号的验证和类型.编译器显示我的编码中有错误的通知,但我无法检测它在哪里.该程序也无法运行.下面是编码,

    import java.util.*;

    public class CreditCard {

        public static void main(String args[]) {
                String CType;(String number) {
                    if (number.startsWith("4"))
                        return "Visa";
                    else if (number.startsWith("5"))
                        return "MasterCard";
                    else if (number.startsWith("6"))
                        return "Discover";
                    else if (number.startsWith("37"))
                        return "American Express";
                    else
                        return "Unknown type";
                };
            Scanner input = new Scanner(System.in);

            System.out.println("Enter a credit card number: ");
            long number = input.nextLong();

            long total = sumOfEvenPlaces(number) + (sumOfOddPlaces(number)*2);

            if (isValid(total)) {
                System.out.println("The "+CType+" card number is valid");
            } else {
                System.out.println("The "+CType+" card number is …