Mask credit card and pin from String in java

Question

Need to mask only 14 digit Credit card number and pin using regular expressions

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Mask{ 
    static String text="+919913623683,,,,1,2,,,4328798712363938,,,,5673,,7,8";
    public static void main(String[] args){
        System.out.println(replaceCreditCardNumber(text));
    }
    public static String  replaceCreditCardNumber(String text){
    String result = text.replaceAll("(\\d{16}(\\b([0-9]{4})[0-9]{0,9}([0-9]{4})\\b))", "$1--HIDDEN--,");
return result;
}
}

Input:

String text="+919913623683,,,,1,2,,,4328798712363938,,,,5673,,7,8";

output:

data="+919913623683,,,,1,2,,,************3988,,,,****,,7,8";

Answer 1

A simple & ugly example using chained replaceAll invocations would look like (note that the order here is important):

String text="+919913623683,,,,1,2,,,4328798712363938,,,,5673,,7,8";
System.out.println(
    text
    //           | not preceded by digit
    //           |      | 4 digits
    //           |      |      | not followed by digit
    //           |      |      |         | replace with literal ****
    .replaceAll("(?<=\\D)\\d{4}(?=\\D)", "****")
    //           | 12 digits
    //           |      | followed by 4 digits
    //           |      |            | replace with literal 12 *s
    .replaceAll("\\d{12}(?=\\d{4})", "************")
);

Output

+919913623683,,,,1,2,,,************3938,,,,****,,7,8

As mentioned, you need the first replaceAll invocation first. Otherwise you'd end up replacing the full 16-digit chunk with "*s", as it would match the condition for the 4-digit replaceAll .