Scala:如何屏蔽字符串的前N个字符

Question

给定一个代表信用卡号的字符串......

val creditCardNo = "1111222233334444"

...如何用前缀12个字符*？

val maskedCreditCardNo = "************4444"

Answer 1

只需使用drop或substring在原始号码上,并添加正确的"*"号码:

"*" * 12 + (creditCardNo drop 12)

Answer 2

替换所有数字符号,除非剩下4个字符:

creditCardNo.replaceAll("\\d(?=\\d{4})", "*")