How do I figure out if an array contains an element?
I thought there might be something like [1, 2, 3].includes(1) which would evaluate as true.
8 Answers
Some syntactic sugar
1 in [1,2,3]
6 Comments
Jesse Glick
Careful.
def m = [a: true]; 'a' in m → true yet def m = [a: false]; 'a' in m → false!
Big McLargeHuge
How do you negate this?
Leponzo
@BigMcLargeHuge
!(1 in [1,2,3])wiredniko
The way to deal with
[a:false] is to use contains. [a: false].containsKey('a') -> true
david
@Big McLargeHuge negation is also possible like this:
1 !in [1,2,3] (Membership operator Groovy) |
.contains() is the best method for lists, but for maps you will need to use .containsKey() or .containsValue()
[a:1,b:2,c:3].containsValue(3)
[a:1,b:2,c:3].containsKey('a')
1 Comment
Naeel Maqsudov
And, in addition, to check if a map contains some not null value under a certain key, it is enough to check the following expression
if(aMap["aKey"]==aValue).For lists, use contains():
[1,2,3].contains(1) == true
2 Comments
Harshay Buradkar
Probably you wanted to say [1,2,3].contains(1). Because I am guessing contains function itself already returns a boolean. Why do you want to again compare it with a hardcoded 'true'.
Automatico
@HarshayBuradkar To make really sure
true == true, of course #jokeYou can use Membership operator:
def list = ['Grace','Rob','Emmy']
assert ('Emmy' in list)
Comments
If you really want your includes method on an ArrayList, just add it:
ArrayList.metaClass.includes = { i -> i in delegate }
Comments
IMPORTANT Gotcha for using .contains() on a Collection of Objects, such as Domains. If the Domain declaration contains a EqualsAndHashCode, or some other equals() implementation to determine if those Ojbects are equal, and you've set it like this...
import groovy.transform.EqualsAndHashCode
@EqualsAndHashCode(includes = "settingNameId, value")
then the .contains(myObjectToCompareTo) will evaluate the data in myObjectToCompareTo with the data for each Object instance in the Collection. So, if your equals method isn't up to snuff, as mine was not, you might see unexpected results.
Comments
def fruitBag = ["orange","banana","coconut"]
def fruit = fruitBag.collect{item -> item.contains('n')}
I did it like this so it works if someone is looking for it.
Comments
You can also use matches with regular expression like this:
boolean bool = List.matches("(?i).*SOME STRING HERE.*")
1 Comment
Kutzi
Can you explain how this works? AFAIK there is no 'matches' method on list: 'groovy.lang.MissingMethodException: No signature of method: java.util.ArrayList.matches()'
assert [12,42,33].indexOf(42) == 1