val arr = Array.fill[String](6, 6)("dark")
Unsafe get:
arr(9)(9)
>java.lang.ArrayIndexOutOfBoundsException: 9
I use something like that (but ugly):
arr.lift(2).flatMap(_.lift(2))
>res0: Option[String] = Some(dark)
Is there better way?
2 Answers
If you want something more readable, you could use a for comprehension:
for {
inner <- arr.lift(7)
value <- inner.lift(2)
} yield value
Comments
Turning my comment into an answer:
val arr = Array.fill[String](6, 6)("dark")
implicit class SafeArrayOps[T](arr: Array[Array[T]]) {
def safeGet(x: Int, y: Int) = {
if (x < 0 || x >= arr.length) None
else {
val inner = arr(x)
if (y <= 0 || y >= inner.length) None
else Some(inner(y))
}
}
}
arr.safeGet(2,2) //> res0: Option[String] = Some(dark)
arr.safeGet(7,7) //> res1: Option[String] = None
arr.safeGet(2,7) //> res2: Option[String] = None
arr.safeGet(7,2) //> res3: Option[String] = None
arr.safeGet(-1, 2) //> res4: Option[String] = None
arr.safeGet(2,-1) //> res5: Option[String] = None
answered Aug 2, 2015 at 9:46
The Archetypal Paul
41.9k20 gold badges107 silver badges136 bronze badges
3 Comments
EnverOsmanov
Brilliant! Combining it with @sascha-kolberg answer it looks even better, I think.
The Archetypal Paul
I'm not too bothered about how it looks. I subscribe to the advice of amazon.co.uk/Elements-Programming-Style-Brian-Kernighan/dp/… "Say what you mean simply and directly".
Det
@TheArchetypalPaul I am too bothered about how it looks.
safeGet[T](x:Int, y:Int):Option[T], using whatever code you like (an explicit array-bounds check might be clearest), then make it an implicit operation on Array. Then the ugliness is just in one place...