Email masking Regex Kotlin-CodePudding

all. I want to mask email and am having a little problem.

My code

val email = [email protected]
val p = """^([^@]{2})([^@] )""".toRegex()
val result = email.replace(p) {
 it.groupValues[1]   "*".repeat(it.groupValues[2].length)
}

expected result : mask with * for first two letters && first four letters after @

lu********@****l.com

current result : can mask before @ but not after it

lu********@gmail.com

How can I mask the first 4 letters after @?

CodePudding user response：

For anyone who will see this post later, here I share my code.

Email Mask : lu********@****l.com

val regex = """^([^@]{2})([^@] )([^@]{0}@)([^@]{4})""".toRegex()
val emailMask = args.biometricOtp.otpData.replace(regex) {
    it.groupValues[1]   "*".repeat(it.groupValues[2].length) 
    it.groupValues[3]   "*".repeat(it.groupValues[4].length) }

Phone number Mask : 82103*******

val regex = """([^@]{5})([^@] )""".toRegex()
val smsMask = args.biometricOtp.otpData.replace(regex) {
    it.groupValues[1]   "*".repeat(it.groupValues[2].length) }

CodePudding user response：

You can replace all chars with * that match the following pattern:

(?:\G(?!^)|(?<=^[^@]{2}|@))[^@](?!\.[^.] $)

See the regex demo. Details:

(?:\G(?!^)|(?<=^[^@]{2}|@)) - match @ (with @), or start of string and any two chars other than @ (with (?<=^[^@]{2}), or the end of the previous successful match (with \G(?!^))
[^@] - any one char other than a @
(?!\.[^.] $) - that is not immediately followed with a . and then one or more chars other than . till the end of string.

See the Kotlin demo:

val regex = """(?:\G(?!^)|(?<=^[^@]{2}|@))[^@](?!\.[^.] $)""".toRegex()
val email = "[email protected]"
val emailMask = email.replace(regex, "*")
print(emailMask)
// => lu********@****l.com