请各位java高手帮帮忙~ - JBTALKS.CC

请各位JAVA高手帮帮忙~
我做到 public static int getDigit(int even)到了第二组我就不会了~
小弟先在这里谢谢高手的帮忙

Credit card numbers follwoing cretain pattern. A credit card number must have between 13 and 16 digits. It must start with:
         4 for Visa cards
         5 for Master cards
         37 for American Express cards
         6 for Discover cards
         In 1954, Hans Lubn of IBM proposed an algorithm forvalidating credit card numbers.  The algorithm is useful to determineif a card number
         is entered correctly or if a credit card is scannedcorrectly by a scanner.  Almost all credit card numbers are generatedfollwoing this
         validity check, commonly known as the Luhn check or theMod 10 check, which can be described as follows (for illustraiton,consider the card
         numebr 4388576018402625):

         1) Double every second digit form right to left.  Itdoubling of a digit results in a two-digit number, add up the twodigits to get a
         single-digit number.
            2 * 2 = 4
            2 * 2 = 4
            4 * 2 = 8
            1 * 2 = 2
            6 * 2 = 12(1 + 2 = 3)
            5 * 2 = 10(1 + 0 = 1)
            8 * 2 = 16(1 + 6 = 7)
            4 * 2 = 8
         2) Now add all single-digit numbers from Step 1.
            4 + 4 + 8 + 2 + 3 + 1 + 7 + 8 = 37
         3) Add all digits int the odd places from right toleft in the card number.
            5 + 6 + 0 + 8 + 0 + 7 + 8 + 3 = 37
         4) Sum the results from Step 2 and Step 3.
            37 + 37 = 74
         5)If the result from Step 4 is divisible by 10, the cardnumber is valid: otherwise, it is invalid.  For example4388576018402625 is invalid,
         but the number 4388576018410707 is valid.
         Write a programt hat prompts the user to enter a creditcard number as a long integer. Display whether the number is valid.
         Design your program to use the following methods:

         /** Return true if the card number is valid */
            //public boolean isValid(long number)

         /** Get the result from Step 2*/
            //public static int sumOfEvenPlace(long number)

         /** Return this number if it is a single digit, otherwise,
            return the sum of the two digits */
            //public static int getDigit(int Number)

      /** Return sum of odd place digits in number */
         //public static int sumOfOddPlace(long number)


~叫我宝哥~ 发表于 2010-6-9 01:53 PM

public static void main(String[] args)
{
String cardno;
int digit, total = 0;
Scanner scan= new Scanner(System.in);
System.out.println(" Please Enter The Credit Card Number: ");
cardno=scan.nextLine();
for(int i=(cardno.length()-1);i>=0;i=i--)
{
digit = Integer.parseInt(cardno.charAt(i));
if(i % 2)
total += digit;
else
{
digit *= 2;
total += Math.floor(digit / 10) + (digit % 10);
}
}
if(total % 10)
System.out.print("This is invalid Credit Card No.");
else
System.out.print("Valid Credit Card No.");
}

复制代码

其實只要了解計算的规则，那麼編寫方面就可以按照自己的逻辑方式来做

目前我這個系统没安裝 Java ...
Super-Tomato 发表于 2010-6-9 11:38 PM

厉害。没Java ，没篇写工具都写的出Java句。你写过那么多种语言，不会混乱哦。大小写方面都正确了。 ...
宅男-兜着走发表于 2010-6-10 06:32 AM

import java.util.*;
public class Assignment11 {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Please Key In Card No.");
String cardNo = scan.next();
if(isValid(Long.parseLong(cardNo)))
System.out.println("\n\"" + cardNo + "\"" + " is valid card no.");
else
System.out.println("\n\"" + cardNo + "\"" + " is invalid card no.");
}
public static boolean isValid(long number)
{
String cardNoStr = Long.toString(number);
int cardNoLength = cardNoStr.length();
String firstDigitValidation , secondDigitValidation;
firstDigitValidation = cardNoStr.substring(0 , 1);
secondDigitValidation = cardNoStr.substring(0 , 2);
int result = sumOfEvenPlace(number) + sumOfOddPlace(number);
return
(
cardNoLength >= 13 &&
cardNoLength <= 16 &&
result % 10 == 0 &&
firstDigitValidation.equals("4") ||
firstDigitValidation.equals("5") ||
firstDigitValidation.equals("6") ||
secondDigitValidation.equals("37")
);
}
public static int sumOfEvenPlace(long number)
{
String sNumber = Long.toString(number);
int result = 0;
for(int i=sNumber.length()-1 ;i>0; i-=2){
result += getDigit(Integer.parseInt(sNumber.substring(i-1 , i)));
}
return result;
}
public static int getDigit(int Number)
{
String mulNumber = Integer.toString(Number * 2);
int result = 0;
if(mulNumber.length() > 1)
result = Integer.parseInt(mulNumber.substring(0, 1)) + Integer.parseInt(mulNumber.substring(1, 2));
else
result = Integer.parseInt(mulNumber);
return result;
}
public static int sumOfOddPlace(long number)
{
String sNumber = Long.toString(number);
int result = 0;
for(int i=sNumber.length() ;i>0; i-=2)
{
result+= Integer.parseInt(sNumber.substring(i-1 , i));
}
return result;
}
}

复制代码