Best way to filter a list using other list? I want...

# getting-started

[suhas]

Best way to filter a list using other list?
I want to filter a list of objects with list of ids.
As of now, I am just doing this

ids.forEach { id ->
   val person = persons.find { it.id == id}
   filteredList.add(person)
}

[Rajkumar Singh]

filteredList += persons.filter { it.id in ids} OR persons.filterTo(filteredList) { it.id in ids }

[suhas]

Thanks. @Rajkumar Singh

[ephemient]

if you have a mutable collection, it can be filtered in-place

persons.retainAll { it.id in ids }

[ephemient]

note that both these operations are O(persons.size · ids.size); if persons is not small then it would be better to convert ids to a Set first

[suhas]

hmm. Thanks.