Canonical way for empty Array in Scala?

Question

What is the canonical way to get an empty array in Scala? new Array[String](0) is too verbose.

Answer 1

val emptyArray =  Array.empty[Type]

Answer 2

Array[String]()

You can leave out the [String] part if it can be inferred (e.g. methodThatAlwaysTakesAStringArray( Array() )).

Answer 3

Array() will be enough, most of the times. It will be of type Array[Nothing].

If you use implicit conversions, you might need to actually write Array[Nothing], due to Bug #3474:

def list[T](list: List[T]) = "foobar"
implicit def array2list[T](array: Array[T]) = array.toList

This will not work:

list(Array()) => error: polymorphic expression cannot be instantiated to expected type;
    found   : [T]Array[T]
    required: List[?]
        list(Array())
                  ^

This will:

list(Array[Nothing]()) //Nothing ... any other type should work as well.

But this is only a weird corner case of implicits. It's is quite possible that this problem will disappear in the future.

Answer 4

If the array type is one of the primitives, you can use the shortcuts from scala.Array.

For example for a byte array it would be:

val arr = Array.emptyByteArray

This is useful when the type cannot be inferred and you want to remain less verbose.