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I'm getting an unexpected behaviour with `String.split(regex)` when there are no matches. Does `split()` return "the rest of the string" when a regex match fails? Code in :thread:

```fun main() {
    val regex = Regex("-{3} #")
    val willMatch = """
    ---
    apple: banana
    --- #matches
    Yay
    """
    val willNotMatch = """
    ---
    Not a valid match
    """
    println("Find the number of matches")
    println(regex.findAll(willMatch).count()) // expect 1, got 1
    println(regex.findAll(willNotMatch).count()) // expect 0, got 0

    println("Split and build a map from the matches. Why does size != count from above?")
    println(willMatch.split(regex).map {it.trim()}.associate{it.substringBefore("\n").trim() to it.substringAfter("\n")}.size) // expect 1, got 2
    println(willNotMatch.split(regex).map {it.trim()}.associate{it.substringBefore("\n") to it.substringAfter("\n")}.size) // expect 0, got 1

}```

Playground here: <https://pl.kotl.in/-C7TfpD5T>

split, with a regex or not, always returns at least 1 segment

Just as the Java API docs state:

&gt; If the expression does not match any part of the input then the resulting array has just one element, namely this string.
<https://docs.oracle.com/javase/8/docs/api/java/lang/String.html#split-java.lang.String-int->

Java's string split actually changed behavior between 7 and 8

Kotlin's string split is always consistent though

simpler example to demonstrate:
```"a-b".split('-') == listOf("a", "b")```
there is 1 match and 2 results

Thanks for the confirmation. I guess I'll need to check for matches, then only do the split if the match succeeds.

(the weird edge cases come from empty strings or empty matches)

I'm extracting text that may be split by named blocks ("--- #blockName"). I need the names and the text that follows. But I don't want to split when there is no block name.

so? no matter what, it sounds like you don't want the content before the first match, and so `.split().drop(1)` always gets you what you want whether there is a match or not

or possibly split isn't the right tool anyway, if you can potentially have both named and unnamed blocks

e.g. <https://pl.kotl.in/ZAzlNnaNn> can't be done by just `split()`