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I have two lists:

val list1 = List("asdf", "fdas", "afswd", "dsf", "twea", "rewgds", "werwe", "dsadfs");
val list2 = List();

I want to filter all items from list1 and setup list2 so that it only contains items that don't contain the letter 'a'. I know how to do this with imperative programming, but how would I do this with functional programing?

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2 Answers 2

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5

Almost literal representation of your requirement definition: 

val list2 = list1.filterNot(item => item.contains('a'))
// List[String] = List(dsf, rewgds, werwe)
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3 Comments

Thanks, I guess what I really need though is to figure out something that doesn't have a default implementation already by Scala. Let's say I have an object and I want to call getId() on each object and then return only the items whose ID contains an 'a' character?
I deleted my post that illustrated this but iterating through would work for any object.
@TritonMan it will be quite the same: xs.filter(obj => obj.getId.contains('a')) (note, filterNot versus filter). One might write the former code as list1.filter(item => !item.contains('a')), but I prefer this filter/filterNot way.
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In response to your comment on @om-nom-nom's answer:

val list2 = for(item <- list1 if !item.contains("a")) yield item
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3 Comments

Just as a side note, both @cmbaxter and mine solutions will be desugared to a nearly the same code.
yeah I think I get that. Also, it looks like maybe I can use _.contains() instead of the "item => item.contains()". Is that the same thing?
@TritonMan yep, it is shorthand syntax

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