I have a very simple string like this one:
"Some(1234)"
I'd like to extract "1234" out from it. How can I do it?
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4 Answers
val s = "Some(1234)"
//s: java.lang.String = Some(1234)
val Pattern = """Some\((\d+)\)""".r
//Pattern: scala.util.matching.Regex = Some\((\d+)\)
val Pattern(number) = s
//number: String = 1234
Switch out your regex for whatever you need. \d+ limits it to digits only.
3 Comments
zinking
what if it didn't match ?
Akos Krivachy
A
scala.MatchError will be thrown.
Albert Hendriks
I have multiple parenthesis-pairs, how do I get the correct match?
scala> val s = "Some(1234)"
s: String = Some(1234)
scala> val nums = "[0-9]".r
nums: scala.util.matching.Regex = [0-9]
scala> nums.findAllIn(s).mkString
res0: String = 1234
Comments
Starting Scala 2.13, it's possible to pattern match a Strings by unapplying a string interpolator:
val s"Some($number)" = "Some(1234)"
// number: String = 1234
Also note that if the idea is to extract an Option[Int] from its toString version, you can use the interpolation extraction with a match statement:
x match { case s"Some($number)" => number.toIntOption case _ => None }
// x = "Some(1234)" => Option[Int] = Some(1234)
// x = "Some(1S3R)" => Option[Int] = None
// x = "None" => Option[Int] = None
Comments
just another way, playing with the regex. Limit to 4 digits.
def getnumber (args: Array[String]) {
val str = "Some(1234)"
val nums = "\\d{4}".r
println (nums.findAllIn(str).mkString)
}
