inline fun <K, V> Map<out K, V>.filterKeys( predicate: (K) -> Boolean ): Map<K, V>
Returns a map containing all key-value pairs with keys matching the given predicate.
The returned map preserves the entry iteration order of the original map.
import kotlin.test.*
import java.util.*
fun main(args: Array<String>) {
//sampleStart
val originalMap = mapOf("key1" to 1, "key2" to 2, "something_else" to 3)
val filteredMap = originalMap.filterKeys { it.contains("key") }
println(filteredMap) // {key1=1, key2=2}
// original map has not changed
println(originalMap) // {key1=1, key2=2, something_else=3}
val nonMatchingPredicate: (String) -> Boolean = { it == "key3" }
val emptyMap = originalMap.filterKeys(nonMatchingPredicate)
println(emptyMap) // {}
//sampleEnd
}
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Licensed under the Apache License, Version 2.0.
https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/filter-keys.html