Scala check if an item is in the list

Question

I need to check if a string is in the list and call a function that takes a boolean accordingly.

Can this be achieved with a single liner?

The code below is the best I could get:

val strings = List("a", "b", "c") val myString = "a" strings.find(x=>x == myString) match { case Some(_) => myFunction(true) case None => myFunction(false) } 

I am sure that this can be done with less coding, but I do not know how to do this.

Answer 1

Just use contains

 myFunction(strings.contains(myString)) 

Answer 2

And if you do not want to use strict equality, you can use exists:

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

Answer 3

Even easier!

 strings contains myString 

Answer 4

this should work with another predicate as well

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

Answer 5

In your case, I would consider using Set rather than List to make sure that you only have unique values. if you don’t need to include duplicates sometimes.

In this case, you do not need to add any wrapper functions around the lists.

Answer 6

You can also implement the contains method with foldLeft , which is 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) } }