Scala capture group using regex

Question

Let's say I have this code:

val string = "one493two483three" val pattern = """two(\d+)three""".r pattern.findAllIn(string).foreach(println) 

I expected findAllIn to only return 483, but instead, it returned two483three. I know I could use unapply to extract only that part, but I'd have to have a pattern for the entire string, something like:

 val pattern = """one.*two(\d+)three""".r  val pattern(aMatch) = string  println(aMatch) // prints 483 

Is there another way of achieving this, without using the classes from java.util directly, and without using unapply?

Answer 1

Here's an example of how you can access group(1) of each match:

val string = "one493two483three" val pattern = """two(\d+)three""".r pattern.findAllIn(string).matchData foreach {    m => println(m.group(1)) } 

This prints "483" (as seen on ideone.com).

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The lookaround option

Depending on the complexity of the pattern, you can also use lookarounds to only match the portion you want. It'll look something like this:

val string = "one493two483three" val pattern = """(?<=two)\d+(?=three)""".r pattern.findAllIn(string).foreach(println) 

The above also prints "483" (as seen on ideone.com).

References

• regular-expressions.info/Lookarounds