Access element of list.toArray by index

Question

I want to access via one-liner a list-to-array element by index.

This gives me an error:

Array(1,2,3)(2)  // 3
List(1,2,3).toArray(2) // error 
(List(1,2,3).toArray)(2) // error

// error: type mismatch;
// found   : scala.this.Int(2)
// required: reflect.this.ClassTag[?]

However, this works:

val a = Array(1,2,3)
val b = List(1,2,3).toArray


println(a(2))  // 3
println(b(2))  // 3

Why is that so and how to make a solution without making extra val's?

Scalafiddle

Why not simply b(2)? If you are only going to access it one time, it would be more efficient this way. Other alternative (if you still want to make the conversion) is b.toArray.apply(2). — Luis Miguel Mejía Suárez
– Luis Miguel Mejía Suárez, Commented Sep 20, 2019 at 20:01

munk · Accepted Answer · 2019-09-20 19:58:11Z

1

The type checker is making the wrong choice. Try giving it a hint.

println((List(1,2,3).toArray: Array[Int])(2))

answered Sep 20, 2019 at 19:58

munk

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