kotlin-stdlib/kotlin.collections/containsValue

containsValue

inline fun <K, V> Map<K, V>.containsValue(value: V): Boolean(source)

Returns true if the map maps one or more keys to the specified value.

Allows to overcome type-safety restriction of containsValue that requires to pass a value of type V.

Since Kotlin

1.1

Samples

import kotlin.test.*
import java.util.*

fun main() { 
   //sampleStart 
   val map: Map<String, Int> = mapOf("x" to 1, "y" to 2)

// member containsValue is used
println("map.containsValue(1) is ${map.containsValue(1)}") // true

// extension containsValue is used when the argument type is a supertype of the map value type
println("map.containsValue(1 as Number) is ${map.containsValue(1 as Number)}") // true
println("map.containsValue(2 as Any) is ${map.containsValue(2 as Any)}") // true

println("map.containsValue(\"string\" as Any) is ${map.containsValue("string" as Any)}") // false

// map.containsValue("string") // cannot call extension when the argument type and the map value type are unrelated at all 
   //sampleEnd
}
inline fun <K, V> Map<K, V>.containsValue(value: V): Boolean(source)

Returns true if the map maps one or more keys to the specified value.

Allows to overcome type-safety restriction of containsValue that requires to pass a value of type V.

Since Kotlin

1.0

Samples

import kotlin.test.*
import java.util.*

fun main() { 
   //sampleStart 
   val map: Map<String, Int> = mapOf("x" to 1, "y" to 2)

// member containsValue is used
println("map.containsValue(1) is ${map.containsValue(1)}") // true

// extension containsValue is used when the argument type is a supertype of the map value type
println("map.containsValue(1 as Number) is ${map.containsValue(1 as Number)}") // true
println("map.containsValue(2 as Any) is ${map.containsValue(2 as Any)}") // true

println("map.containsValue(\"string\" as Any) is ${map.containsValue("string" as Any)}") // false

// map.containsValue("string") // cannot call extension when the argument type and the map value type are unrelated at all 
   //sampleEnd
}