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?
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3 Answers
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.)
Comments
You can do:
map.values.toSet.contains("")
or:
map find { case (a,b) => b == "" } isDefined
Comments
Or you can just write:
map contains ""
answered Feb 28, 2011 at 19:29
Antonin Brettsnajdr
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1 Comment
michael.kebe
This is wrong. He wants to check if the map contains a value with the value
"". Not the key as you proposed.