Kotlin List maxOfOrNull()
Syntax & Examples

Syntax of List.maxOfOrNull()

The syntax of List.maxOfOrNull() extension function is:

fun <T> Iterable<T>.maxOfOrNull( selector: (T) -> Double ): Double?

This maxOfOrNull() extension function of List returns the largest value among all values produced by selector function applied to each element in the collection or null if there are no elements.


✐ Examples

1 Example

In this example,

  • We create a list named list containing the doubles 10.5, 20.3, 15.8, 30.1.
  • We apply the maxOfOrNull function to list, which takes a lambda with one parameter: it.
  • Within the lambda, it represents each element of the list.
  • The lambda simply returns each element as is.
  • The maxOfOrNull function returns the largest value among all values produced by the lambda.
  • Finally, we print the result to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf(10.5, 20.3, 15.8, 30.1);
    val result = list.maxOfOrNull { it }
    print(result);
}

Output

30.1

2 Example

In this example,

  • We create a list named list containing the strings 'a', 'b', 'c'.
  • We apply the maxOfOrNull function to list, which takes a lambda with one parameter: it.
  • Within the lambda, it represents each element of the list.
  • We convert each character to its length as a double.
  • The maxOfOrNull function returns the largest length among all strings in the list.
  • Finally, we print the result to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf(&quot;a&quot;, &quot;b&quot;, &quot;c&quot;);
    val result = list.maxOfOrNull { it.length.toDouble() }
    print(result);
}

Output

1.0

3 Example

In this example,

  • We create a list named list containing the strings 'apple', 'banana', 'cherry'.
  • We apply the maxOfOrNull function to list, which takes a lambda with one parameter: it.
  • Within the lambda, it represents each element of the list.
  • We convert each string to its length as a double.
  • The maxOfOrNull function returns the largest length among all strings in the list.
  • Finally, we print the result to standard output.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf(&quot;apple&quot;, &quot;banana&quot;, &quot;cherry&quot;);
    val result = list.maxOfOrNull { it.length.toDouble() }
    print(result);
}

Output

6.0

Summary

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