Question

How to mask a number with stars except the last 4 digits in Java

Answer 1

public class Program {
    public static String mask_number_with_stars_except_the_last_4_digits(String cardNumber) {
        String last4Digits = cardNumber.substring(cardNumber.length() - 4);

        String maskedNumber = String.format("%1$" + cardNumber.length() + "s", last4Digits).replace(' ', '*');
        
        return maskedNumber;
    }
    
    public static void main(String[] args) {
        String cardNumber = "9003125334656789";

        String maskedNumber = mask_number_with_stars_except_the_last_4_digits(cardNumber);

        System.out.println(maskedNumber);


    }
}


 
/*
run
 
************6789
 
*/

 

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