Question 126394 in Android Studio Question posted in
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Android Studio – Regex in kotlin

I’m trying to use substringBefore() fun with two char ("#" and "&").
How can i use regex for both cahrs?
I dont want to do this:

if (myString.contains("&")) {            
    myString.substringBefore("&")    
} else if (myString.contains("#"))
    myString.substringBefore("#")
}
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3

Answers


  1. Chosen as BEST ANSWER
    0

    Finally I've found a way and it is actually easy:

     val matchRegex = "[#&]".toRegex().find(myString)
 val manipulatedString = matchRegex?.range?.first?.let {
   myString.substring(0, it)
 }

    This will return NULL if there is no regex chars in the string or, the subString before those chars


  2. 0

    If I understand correctly, substringBefore() does not accept a regex parameter. However, replace() does, and we can formulate your problem as removing everything from the first & or # until the end of the string.

    myString.replace(Regex("[&#].*"), "")

    The above single line call to replace would leave unchaged any string not having any & or # in it. If desired, you could still use the if check:

    if (myString.contains("&") || myString.contains("#")) {
    myString.replace(Regex("[&#].*"), "")
}
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  3. 0

    Using RegEx:

    If the result contains neither ‘&’ nor ‘#’ and you want the whole string to be returned:

    val result = myString.split('&', '#').first()

    If the result contains neither ‘&’ nor ‘#’ and you want null to be returned:

    val result = myString.split('&', '#').let { if (it.size == 1) null else it.first() }

    Not using RegEx:

    If the result contains neither ‘&’ nor ‘#’ and you want the whole string to be returned:

    val result = myString.takeWhile { it != '&' && it != '#' }

    If the result contains neither ‘&’ nor ‘#’ and you want null to be returned:

    val result = myString.takeWhile { it != '&' && it != '#' }
  .let { if (it == myString) null else it }
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