Scala check if element is present in a list

Question

I need to check if a string is present in a list, and call a function which accepts a boolean accordingly.

Is it possible to achieve this with a one liner?

The c

Answer 1

In your case I would consider using Set and not List, to ensure you have unique values only. unless you need sometimes to include duplicates.

In this case, you don't need to add any wrapper functions around lists.

Answer 2

You can also implement a contains method with foldLeft, it's pretty awesome. I just love foldLeft algorithms.

For example:

object ContainsWithFoldLeft extends App {

  val list = (0 to 10).toList
  println(contains(list, 10)) //true
  println(contains(list, 11)) //false

  def contains[A](list: List[A], item: A): Boolean = {
    list.foldLeft(false)((r, c) => c.equals(item) || r)
  }
}

Answer 3

Just use contains

myFunction(strings.contains(myString))

Answer 4

this should work also with different predicate

myFunction(strings.find( _ == mystring ).isDefined)

Answer 5

And if you didn't want to use strict equality, you could use exists:

myFunction(strings.exists { x => customPredicate(x) })

Answer 6

Even easier!

strings contains myString