Question

I have a newbie question.

We can use contains to check if a map contain a specified key, as:

val map = Map("a"->"1", "b"->"")
map.contains("a")

But now, I want to check if the map contains an empty string, is there any method to use?

Answer 1

Try

map.values.exists(_ == "")

---

Edit: I think the above is the clearest, but I can’t resist showing two others.

map.exists(_._2 == "")

is more compact, but you have to remember that _2 is the value when you iterate through a map.

map.values.exists(""==)

is an alternative form of the original, where instead of explicitly comparing the argument with _ == "", you supply an equality function "".equals _ or ""== for short. (Two ways of looking at the same thing–is it the empty string supplying its equals method for testing, or is it your closure testing the elements against the empty string? I think the latter (the original) is considerably clearer.)