Kotlin Tutorials

Kotlin Map any()
Syntax & Examples

Syntax of Map.any()

There are 2 variations for the syntax of Map.any() extension function. They are:

1.
fun <K, V> Map<out K, V>.any(): Boolean

This extension function returns true if map has at least one entry.

2.
fun <K, V> Map<out K, V>.any( predicate: (Entry<K, V>) -> Boolean ): Boolean

This extension function returns true if at least one entry matches the given predicate.


✐ Examples

1 Check if any entry exists in the map

In this example,

  • We create a map named map1 with three key-value pairs.
  • We then use the any() function to check if map1 has at least one entry, which it does.
  • The result, which is true, is printed to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val map1 = mapOf('a' to 1, 'b' to 2, 'c' to 3)
    val result = map1.any()
    println(result)
}

Output

true

2 Check if any entry matches a predicate in the map

In this example,

  • We create a map named map2 with three key-value pairs.
  • We then use the any() function with a predicate that checks if any entry's value is equal to 2 in map2.
  • As one entry ('b' -> 2) matches the predicate, the result is true, which is printed to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val map2 = mapOf('a' to 1, 'b' to 2, 'c' to 3)
    val result = map2.any { entry -> entry.value == 2 }
    println(result)
}

Output

true

3 Check if any entry with a specific key exists in the map

In this example,

  • We create a map named map3 with three key-value pairs.
  • We then use the any() function with a predicate that checks if any entry's key is equal to 'd' in map3.
  • As no entry has a key 'd', the result is false, which is printed to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val map3 = mapOf('a' to 1, 'b' to 2, 'c' to 3)
    val result = map3.any { entry -> entry.key == 'd' }
    println(result)
}

Output

false

Summary

In this Kotlin tutorial, we learned about any() extension function of Map: the syntax and few working examples with output and detailed explanation for each example.