Scala: Splitting with Double Quotes (“”) vs Single Quotes ('')

Question

I am splitting a String in Scala with Comma using Double Quotes, like this:

scala> val a = \"a,b,c\"
a: String = a,b,c

scala> a.split(\",\")
res0: Arr         


        

Answer 1

Split by char or escape if you string by string.

Use it as char

scala> a.split('|')
res5: Array[String] = Array(a, b, c)

It works, you need to use escape sequence. Pipe (|) has a special meaning. You need to use escape sequence to say its a normal char.

scala> val a = "a|b|c"
a: String = a|b|c

scala> a.split("\\|")
res2: Array[String] = Array(a, b, c)

with triple quotes

scala> a.split("""\|""")
res4: Array[String] = Array(a, b, c)

Answer 2

Pipe (|) is a metacharacter in regex. You'd need to escape it:

scala> a.split("\\|")
res1: Array[String] = Array(a, b, c)

Answer 3

First of all '|' is Char whereas "|" is String.

scala> val a1 = '|'
// a1: Char = |

scala> val a2 = "|"
// a2: String = |

Now, when you pass a String to String.split it uses it to create a a regular expression, which is then used to split the String.

And | is a special character in regular expressions.

Which means that you need to escape your | so that it will not be considered as a special character. In regular expressions, we use \ to mark the next character as escaped.

scala> val a = "a|b|c"
// a: String = a|b|c

scala> a.split(raw"\|")
// res2: Array[String] = Array(a, b, c)


scala>a.split("\\|")
// res0: Array[String] = Array(a, b, c)

Or,

scala> val a = "a|b|c"
// a: String = a|b|c

scala> val regex = raw"\|".r
// regex: scala.util.matching.Regex = \|

scala> regex.split(a)
// res1: Array[String] = Array(a, b, c)

Notice that \\| and \| difference when not using raw, that is because \ is a special character in Scala Strings.

So when we are not using raw String we have to first tell that the next \ is not a special character and will not be processed by String, hence left as it is. So the processed String will look like \|.

Answer 4

The split method is overloaded. If you use single quote ' you are splitting by a character:

def split(separator: Char)

If you use double quote " you are using java split that takes a regex:

public String[] split(String regex)

Since pipe | is a reserved character in a regex you need to escape it if you are using double quotes:

a.split("\\|")