A method's type signature comprises its name; the number, order, and types of its parameters, if any; and its result type. The type signature of a class, trait, or singleton object comprises its name, the type signatures of all of its members and constructors, and its declared inheritance and mixin relations.
In Java you declare a generic type within a <>, in Scala [] is used:
Most of the time, Scala will infer the type and [] are optional:
val z = "Do" :: "Re" :: "Mi" :: "Fa" :: "So" :: "La" :: "Te" :: "Do" :: Nil //Infers that the list assigned to variable is of type List[String]
A trait can be declared containing a type, where a concrete implementer will satisfy the type:
trait Randomizer[A] {
def draw(): A
}
class IntRandomizer extends Randomizer[Int] {
def draw() = {
import util.Random
Random.nextInt()
}
}
val intRand = new IntRandomizer
(intRand.draw <= Int.MaxValue) should be(res0)
Class meta-information can be retrieved by class name by using classOf[className]:
classOf[String].getCanonicalName should be(res0)
classOf[String].getSimpleName should be(res1)
Class meta-information can be derived from an object reference using getClass():
val zoom = "zoom"
zoom.isInstanceOf[String] should be(res0)
zoom.getClass.getCanonicalName should be(res1)
zoom.getClass.getSimpleName should be(res2)
isInstanceOf[className] is used to determine if an object reference is an instance of a given class:
trait Randomizer[A] {
def draw(): A
}
class IntRandomizer extends Randomizer[Int] {
def draw() = {
import util.Random
Random.nextInt()
}
}
val intRand = new IntRandomizer
intRand.isInstanceOf[IntRandomizer] should be(res0)
intRand.isInstanceOf[Randomizer[Int]] should be(res1)
intRand.draw.isInstanceOf[Int] should be(res2)
