Kotlin Tutorials

Kotlin Map maxWith()
Syntax & Examples

Syntax of Map.maxWith()

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

1.
fun <K, V> Map<out K, V>.maxWith( comparator: Comparator<in Entry<K, V>> ): Entry<K, V>

This extension function returns the first entry having the largest value according to the provided comparator.

2.
fun <K, V> Map<out K, V>.maxWith( comparator: Comparator<in Entry<K, V>> ): Entry<K, V>?

This extension function


✐ Examples

1 Get entry with the largest value

In this example,

  • We create a map named map1 with key-value pairs {'apple': 3, 'banana': 1, 'cherry': 2}.
  • We then apply the maxWith() function on map1, using the comparator compareBy { it.value } to compare entries based on their values.
  • As a result, the entry with the largest value ('apple': 3) is returned.
  • We print the result to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val map1 = mapOf("apple" to 3, "banana" to 1, "cherry" to 2)
    val result = map1.maxWith(compareBy { it.value })
    println(result)
}

Output

apple=3

2 Get entry with the largest key

In this example,

  • We create a map named map2 with key-value pairs {1: 'apple', 2: 'banana', 3: 'cherry'}.
  • We then apply the maxWith() function on map2, using the comparator compareBy { it.key } to compare entries based on their keys.
  • As a result, the entry with the largest key (3: 'cherry') is returned.
  • We print the result to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val map2 = mapOf(1 to "apple", 2 to "banana", 3 to "cherry")
    val result = map2.maxWith(compareBy { it.key })
    println(result)
}

Output

3=cherry

3 Get entry with the largest numeric value

In this example,

  • We create a map named map3 with key-value pairs {'apple': 5, 'banana': 7, 'cherry': 3}.
  • We then apply the maxWith() function on map3, using the comparator compareBy { it.value } to compare entries based on their values.
  • As a result, the entry with the largest numeric value ('banana': 7) is returned.
  • We print the result to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val map3 = mapOf("apple" to 5, "banana" to 7, "cherry" to 3)
    val result = map3.maxWith(compareBy { it.value })
    println(result)
}

Output

banana=7

Summary

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