I'd like to convert an Array[String] to an Array[Int], using map method. What is the shortest way to get a function of type (String) => Int to pass as map argument?
I'd prefer convert existing builtin ones like Integer.valueOf in some way.
A method of argument binding to shorten the construction like def parseInt(s:String) = Integer.parseInt(s, 10) would also be great.
scala> Array("1", "2", "3") map(_.toInt)
res4: Array[Int] = Array(1, 2, 3)
or
scala> def parseInt(s:String) = Integer.parseInt(s, 10)
parseInt: (s: String)Int
scala> Array("1", "2", "3") map parseInt
res7: Array[Int] = Array(1, 2, 3)
First, let's define an array of strings:
scala> val foo = Array("1", "2", "3")
foo: Array[java.lang.String] = Array(1, 2, 3)
The most obvious way would be to use Scala's toInt(), available on strings:
Definition:
// StringLike.scala
def toInt: Int = java.lang.Integer.parseInt(toString)
(Note: toString, defined elsewhere, simply converts the StringLike object to a Java string)
Your code:
scala> foo.map(_.toInt)
res0: Array[Int] = Array(1, 2, 3)
Integer.valueOf() also works, but notice you will get Array[Integer] instead of Array[Int]:
scala> foo.map(Integer.valueOf)
res1: Array[java.lang.Integer] = Array(1, 2, 3)
While we're at it, a for comprehension would work almost as well, except you'd be invoking toInt yourself, instead of passing it over to map()
scala> for (i<-foo) yield i.toInt
res2: Array[Int] = Array(1, 2, 3)
It's as simple as:
Array("1", "2", "3") map Integer.valueOf
scala> val strs = Array("1", "2")
strs: Array[java.lang.String] = Array(1, 2)
scala> strs.map(_.toInt)
res0: Array[Int] = Array(1, 2)
