Kotlin’s any operation answers a practical collection question: does at least one element satisfy this predicate? It returns a Boolean and expresses the intent directly, without manually looping or counting matches. section 6.1.3
Check whether someone qualifies
val canBeInClub27 = { p: Person -> p.age <= 27 } val people = listOf(Person("Alice", 27), Person("Bob", 31)) println(people.any(canBeInClub27)) // true The lambda defines the condition; any applies it to the collection and succeeds because Alice matches. The predicate can also be written inline: people.any { it.age <= 27 }. section 6.1.3
Choose the predicate operation that matches the question:
- Use any when at least one element must match. section 6.1.3
- Replace !all with any and a negated predicate when that wording is clearer: !list.all { it == 3 } becomes list.any { it != 3 }. section 6.1.3
- Replace !any with none when the question is whether no elements match. section 6.1.3
- Remember that any returns false for an empty collection because no element can satisfy the predicate. section 6.1.3
- Use count when you need the number of matching elements, or find when you need the first matching element. section 6.1.3
Predicates are Boolean-returning lambdas, so the same style applies across collections and sequences. Prefer any over a negated all or a manual search when it makes the requirement easier to read and maintain. section 6.3 section 6.1.3
