Kotlin List maxWithOrNull()
Syntax & Examples

Syntax of List.maxWithOrNull()

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

fun <T> Iterable<T>.maxWithOrNull( comparator: Comparator<in T> ): T?

This maxWithOrNull() extension function of List returns the first element having the largest value according to the provided comparator or null if there are no elements.

✐ Examples

1 Example

In this example,

We create a list named list containing the numbers [3, 1, 4, 1, 5, 9, 2, 6].
We apply maxWithOrNull() function with the natural order comparator to find the first element having the largest value.
Since the list is not empty, the first element having the largest value is determined using the natural order comparator.
The first element with the largest value, which is 9, is stored in result.
Finally, we print the value of result to standard output using the print statement.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf(3, 1, 4, 1, 5, 9, 2, 6);
    val result = list.maxWithOrNull(Comparator.naturalOrder());
    print(result);
}

Output

2 Example

In this example,

We create a list named list containing the characters ['a', 'p', 'p', 'l', 'e'].
We apply maxWithOrNull() function with the reverse order comparator to find the first element having the largest value.
Since the list is not empty, the first element having the largest value is determined using the reverse order comparator.
The first element with the largest value, which is 'a', is stored in result.
Finally, we print the value of result to standard output using the print statement.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf('a', 'p', 'p', 'l', 'e');
    val result = list.maxWithOrNull(Comparator.reverseOrder());
    print(result);
}

Output

3 Example

In this example,

We create a list named list containing the strings ['apple', 'banana', 'orange', 'grape'].
We apply maxWithOrNull() function with a comparator based on the length of the strings to find the first string with the largest length.
Since the list is not empty, the first string with the largest length is determined using the length-based comparator.
The first string with the largest length, which is 'banana', is stored in result.
Finally, we print the value of result to standard output using the print statement.

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf("apple", "banana", "orange", "grape");
    val result = list.maxWithOrNull(compareBy { it.length });
    print(result);
}

Output

banana

Summary

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