I have Return type masked Credit Card from which I need to Find Card Type

Question

I am Passing creditCardNumber as 4242***4242 which is masked. How I can get Card Type based on Masked credit card number?

    String regVisa = "^4[0-9]{2}(?:[0-9]{3})?$";
    String reVisa = "(?:4[0-9]{12}(?:[0-9]{3})?$)";
    String regMaster = "^5[1-5][0-9]{14}$";
    String regExpress = "^3[47][0-9]{13}$";
    String regDiners = "^3(?:0[0-5]|[68][0-9])[0-9]{11}$";
    String regDiscover = "^6(?:011|5[0-9]{2})[0-9]{12}$";
    String regJCB= "^(?:2131|1800|35\\d{3})\\d{11}$";


    if(creditCardNumber.matches(regVisa))
        return "visa";
    if (creditCardNumber.matches(regMaster))
        return "mastercard";
    if (creditCardNumber.matches(regExpress))
        return "amex";
    if (creditCardNumber.matches(regDiners))
        return "DINERS";
    if (creditCardNumber.matches(regDiscover))
        return "discover";
    if (creditCardNumber.matches(regJCB))
        return "jcb";
    if (creditCardNumber.matches(reVisa))
        return "VISA";
    return "invalid";

Answer 1

Maybe, you have to design some "masked" expression for each, such as:

^4[0-9]{2}[0-9]\\*{3}[0-9]{4}$

Test

import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class re{

    public static void main(String[] args){

    final String regex = "^4[0-9]{2}[0-9]\\*{3}[0-9]{4}$";
    final String string = "4242***4242\n"
         + "5242***4242";

    final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
    final Matcher matcher = pattern.matcher(string);

    while (matcher.find()) {
        System.out.println("Full match: " + matcher.group(0));
        for (int i = 1; i <= matcher.groupCount(); i++) {
            System.out.println("Group " + i + ": " + matcher.group(i));
        }
    }

    }
}

Output

Full match: 4242***4242

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If you wish to explore/simplify/modify the expression, it's been explained on the top right panel of regex101.com . If you'd like, you can also watch in this link , how it would match against some sample inputs.

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RegEx Circuit

jex.im visualizes regular expressions: