Using varargs from Scala

问题

I'm tearing my hair out trying to figure out how to do the following:

def foo(msf: String, o: Any, os: Any*) = {
    println( String.format(msf, o :: List(os:_*)) )
}

There's a reason why I have to declare the method with an o and an os Seq separately. Basically, I end up with the format method called with a single object parameter (of type List). Attempting:

def foo(msf: String, o: Any, os: Any*) = {
    println( String.format(msf, (o :: List(os:_*))).toArray )
}

Gives me the type error:

found: Array[Any]

required Seq[java.lang.Object]

I've tried casting, which compiles but fails for pretty much the same reason as the first example. When I try

println(String.format(msg, (o :: List(os:_*)) :_* ))

this fails to compile with implicit conversion ambiguity (any2ArrowAssoc and any2stringadd)

回答1:

def foo(msf: String, o: AnyRef, os: AnyRef*) = 
  println( String.format(msf, (o :: os.toList).toArray : _* ))

回答2:

def foo(msf: String, o: AnyRef, os: AnyRef*) =
  println( String.format(msf, o :: os.toList : _* ) )

or

def foo(msf: String, o: AnyRef, os: AnyRef*) =
      println( msf format (o :: os.toList : _* ) )

I much prefer the latter, though it has no locale* support.

• Scala 2.8 does have locale support with RichString's format.

来源：https://stackoverflow.com/questions/1008783/using-varargs-from-scala