Could you guys please tell me what I'm doing incorrectly trying to extract using regex pattern-matching? I have following code
val Pattern = "=".r
val Pattern(key, value) = "key=value"
And I get following exception in runtime
Exception in thread "main" scala.MatchError: key=value (of class java.lang.String)
That's more of a regular expression problem: your regex does not capture any groups, it just matches a single = character.
With
val Pattern = "([^=]*)=(.*)".r
you will get:
scala> val Pattern(key, value) = "key=value"
key: String = key
value: String = value
Edit:
Also, that won't match if the input string is empty. You can change the pattern to make it match, or (better) you can pattern match with the regex, like so:
"key=value" match {
case Pattern(k, v) => // do something
case _ => // wrong input, do nothing
}
If what you actually wanted was to split the input text with whatever the regex matches, that is also possible using Regex.split:
scala> val Pattern = "=".r
Pattern: scala.util.matching.Regex = =
scala> val Array(key, value) = Pattern.split("key=value")
key: String = key
value: String = value
val Pattern = "([^=]*)=?(.*)".r just in case an empty string is passed in.