I am trying to use regex to extract a substring from a given string. I am doing this in Scala:
val pattern = Pattern.compile("(Word)+")
val matcher = pattern.matcher("WordWordRestOfString")
matcher.group(1)
The desired output is "WordWord", however, I keep getting an IllegalStateException. I haven't really worked with Regex before, and cannot fully grasp how the matcher.group method works, but I have seen answers to questions suggesting the use of matcher.group(1).
First of all, the repeated capturing group only keeps the last captured value in the group memory buffer, so it is not surprising you onyl get Word as Group 1 value. See the Repeating a Capturing Group vs. Capturing a Repeated Group.
Second, you do not actually call the matcher .find or .matches method that actually trigger the regex search.
Third, you do not need to get Group 1 value here, you just need to get a full match:
val s = "WordWordRestOfStringWordWordWord"
val pattern = "(Word)+".r
// Single result:
val result = pattern.findFirstMatchIn(s).get
println(result) // => WordWord
// Multiple results:
val multiple_results = pattern.findAllMatchIn(s)
println(multiple_results.mkString(", ")) // => WordWord, WordWordWord
See the Scala demo