信用卡类型和验证
我想运行一个程序，可以根据输入的号码确定信用卡号码的确认和类型。 编译器显示通知我的代码有错误，但我无法检测到它在哪里。 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 invalid.");
}
}
public static boolean isValid(long total) {
if (total % 10 != 0) {
} else {
return true;
}
return false;
}
public static int sumOfEvenPlaces(long number) {
int sum = 0;
int remainder;
while (number % 10 != 0 || number / 10 != 0) {
remainder = (int) (number % 10);
sum = sum + getDigit(remainder * 2);
number /= 100;
}
return sum;
}
public static int getDigit(int number) {
if (number > 9) {
return (number % 10 + number / 10);
}
return number;
}
public static int sumOfOddPlaces(long number) {
int sum = 0;
int remainder;
number /= 10;
while (number % 10 != 0 || number / 10 != 0) {
remainder = (int) (number % 10);
sum = sum + getDigit(remainder * 2);
number /= 100;
}
return sum;
}
}
我使用enum做卡片类型检测：
package com.gabrielbauman.gist;
import java.util.regex.Pattern;
public enum CardType {
UNKNOWN,
VISA("^4[0-9]{12}(?:[0-9]{3}){0,2}$"),
MASTERCARD("^(?:5[1-5]|2(?!2([01]|20)|7(2[1-9]|3))[2-7])d{14}$"),
AMERICAN_EXPRESS("^3[47][0-9]{13}$"),
DINERS_CLUB("^3(?:0[0-5]d|095|6d{0,2}|[89]d{2})d{12,15}$"),
DISCOVER("^6(?:011|[45][0-9]{2})[0-9]{12}$"),
JCB("^(?:2131|1800|35d{3})d{11}$"),
CHINA_UNION_PAY("^62[0-9]{14,17}$");
private Pattern pattern;
CardType() {
this.pattern = null;
}
CardType(String pattern) {
this.pattern = Pattern.compile(pattern);
}
public static CardType detect(String cardNumber) {
for (CardType cardType : CardType.values()) {
if (null == cardType.pattern) continue;
if (cardType.pattern.matcher(cardNumber).matches()) return cardType;
}
return UNKNOWN;
}
}
然后，您可以执行CardType.detect("cardnumbergoeshere")然后您将返回CardType.VISA等。
要点有单元测试。
为了验证，我有：
public boolean isValid(String cardNumber) {
int sum = 0;
boolean alternate = false;
for (int i = cardNumber.length() - 1; i >= 0; i--) {
int n = Integer.parseInt(cardNumber.substring(i, i + 1));
if (alternate) {
n *= 2;
if (n > 9) {
n = (n % 10) + 1;
}
}
sum += n;
alternate = !alternate;
}
return (sum % 10 == 0);
}
这应该做到这一点。
这可能更符合你想要做的事情：
public static void main(final String args[])
{
String cType = null;
System.out.println("Enter a credit card number: ");
final Scanner input = new Scanner(System.in);
final String cardNumber = input.next();
if (cardNumber.startsWith("4"))
{
cType = "Visa";
}
else if (cardNumber.startsWith("5"))
{
cType = "MasterCard";
}
else if (cardNumber.startsWith("6"))
{
cType = "Discover";
}
else if (cardNumber.startsWith("37"))
{
cType = "American Express";
}
else
{
cType = "Unknown type";
}
final long total = sumOfEvenPlaces(Long.valueOf(cardNumber)) + (sumOfOddPlaces(Long.valueOf(cardNumber)) * 2);
if (isValid(total))
{
System.out.println("The " + cType + " card number is valid");
}
else
{
System.out.println("The " + cType + " card number is invalid.");
}
}
在文体上， CType应该以小写字母（例如cType ） cType 。 您必须尝试使用Scanner以及我不确定我的实施将如何执行您的要求。