Declare variable of type String* in scala [duplicate]

Question

Is there a way to declare a variable of type String* in scala? As in a variable number of arguments? The issue is that when I want to test a series of methods that takes in a String* as a parameter and don't want to just replicate the values I pass in every test. I know that I can change the functions to take in a collection of String like Array or Seq, but I wanted to know if there was a way to do it without changing the parameter types

if you have mySeq which is Seq[String], then you can pass it to a method expecting a String* like this: foo(mySeq: _*) — Seth Tisue
– Seth Tisue, Commented Oct 3, 2018 at 20:23
Oh wow that worked! But why did that work? Are you casting it when you use it in foo()? — User_KS
– User_KS, Commented Oct 3, 2018 at 20:48

jwvh · Accepted Answer · 2018-10-03 22:01:27Z

2

Varargs notation:

def foo(ss :String*) = {
  //ss is Seq[String], you can ss.map(), ss.length, etc.
}

usage:

foo()
foo("this", "that")
foo("abc", "abd", "abx")

val someList = List("another" , "collection", "of", "strings")
foo(someList :_*) // turn a collection into individual varargs parameters

edited Oct 3, 2018 at 22:01

answered Oct 3, 2018 at 21:14

jwvh

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3 Comments

User_KS Over a year ago

Yes but why does this work? What does :_* actually do

Andrey Tyukin Over a year ago

@KianShahangyan It's just a marker that tells the compiler to treat an argument as vararg. It has no other meaning anywhere else. Quote: "The last argument in an application may be marked as a sequence argument, e.g. e: _*.". It's just a rarely used syntax that you have to either memorize, or google under "varargs" next time.

Brian McCutchon Over a year ago

@Kian stackoverflow.com/questions/6051302/…

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