Split strings with separator splited into each characters in Scala

Question

I'm trying to split a text bunch with | bar separator. 123.123.123.123|000.000.000.000 to each ip address blocks. But each numbers are splited not by |.

scala> "123.123.123.123|000.000.000.000".split("|")
res30: Array[java.lang.String] = Array("", 1, 2, 3, ., 1, 2, 3, ., 1, 2, 3, ., 1, 2, 3, |, 0, 0, 0, ., 0, 0, 0, ., 0, 0, 0, ., 0, 0, 0)

scala> "123.123.123.123".split("|")
res33: Array[java.lang.String] = Array("", 1, 2, 3, ., 1, 2, 3, ., 1, 2, 3, ., 1, 2, 3)

So I put the separator as Char and it shows what I intended.

scala> "123.123.123.123|000.000.000.000".split('|')
res31: Array[String] = Array(123.123.123.123, 000.000.000.000)

scala> "123.123.123.123".split('|')
res32: Array[String] = Array(123.123.123.123)

Why does single character make a huge difference?

I've read Scala doc and StringLike.scala, and got no answer.

def split(separators: Array[Char]): Array[String]
def split(separator: Char): Array[String]

Thanks.

Answer 1

Split method accepts either string or character(s). If you use string it will be interpreted as a regexp and "|" is treated as regex 'or' -- in your case it backs to 'every character goes to it's own bin'. Escape it to have raw delimeter:

"123.123.123.123|000.000.000.000".split("\\|")
res1: Array[String] = Array(123.123.123.123, 000.000.000.000)

Character separator is interpreted as is, so you got the desired result without any fuss

Answer 2

Note that, as om-nom-nom correctly mentioned (but didn't provide the example), characters (which are enclosed in single ') are also valid:

"123.123.123.123|000.000.000.000".split('|')

I find this to be more obvious/readable. I'm also assuming that this would be faster, since it does not have to invoke the regex parser. But that is speculation of course, and also unnecessary micro-optimization.