Kotlin List sortedByDescending()
Syntax & Examples

Syntax of List.sortedByDescending()

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

fun <T, R : Comparable<R>> Iterable<T>.sortedByDescending( selector: (T) -> R? ): List<T>

This sortedByDescending() extension function of List returns a list of all elements sorted descending according to natural sort order of the value returned by specified selector function.

✐ Examples

1 Example

In this example,

We define a data class Person with properties name and age.
We create a list of Person objects named list with ages 25, 30, 20.
We use sortedByDescending to sort the list by age in descending order.
The sorted list is stored in sortedList.
We print sortedList using println().

Kotlin Program

fun main(args: Array<String>) {
    data class Person(val name: String, val age: Int)
    val list = listOf(Person("Alice", 25), Person("Bob", 30), Person("Charlie", 20))
    val sortedList = list.sortedByDescending { it.age }
    println(sortedList)
}

Output

[Person(name=Bob, age=30), Person(name=Alice, age=25), Person(name=Charlie, age=20)]

2 Example

In this example,

We create a list of characters named list containing elements 'b', 'a', 'd', 'c', 'e'.
We use sortedByDescending with the identity function { it } to sort the list in descending order.
The sorted list is stored in sortedList.
We print sortedList using println().

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf('b', 'a', 'd', 'c', 'e')
    val sortedList = list.sortedByDescending { it }
    println(sortedList)
}

Output

[e, d, c, b, a]

3 Example

In this example,

We create a list of strings named list containing elements "banana", "apple", "date", "cherry".
We use sortedByDescending with the length function { it.length } to sort the list in descending order based on string length.
The sorted list is stored in sortedList.
We print sortedList using println().

Kotlin Program

fun main(args: Array<String>) {
    val list = listOf("banana", "apple", "date", "cherry")
    val sortedList = list.sortedByDescending { it.length }
    println(sortedList)
}

Output

[banana, cherry, apple, date]

Summary

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