sortByDescending

kotlin-stdlib/kotlin.collections/sortByDescending

С версии Kotlin: 1.0

inline fun <T, R : Comparable<R>> Array<out T>.sortByDescending(crossinline selector: (T) -> R?)

Сортирует элементы массива на месте в порядке убывания согласно естественному порядку сортировки значений, возвращаемых указанной функцией селектора.

Сортировка устойчивая. Это означает, что элементы, для которых селектор вернул равные значения, после сортировки сохраняют взаимный порядок.

Примеры

import kotlin.math.*
import kotlin.test.*

fun main() { 
   //sampleStart 
   class Dish(val name: String, val calories: Int, val tasteRate: Float) {
    override fun toString(): String = "Dish($name: $calories cal, taste $tasteRate/5)"
}

val fridgeContent = mutableListOf(
    Dish("🍨", 207, 4.7f),
    Dish("🥦", 34, 2.3f),
    Dish("🧃", 34, 4.9f)
)

// original order
println(fridgeContent) // [Dish(🍨: 207 cal, taste 4.7/5), Dish(🥦: 34 cal, taste 2.3/5), Dish(🧃: 34 cal, taste 4.9/5)]

// sort by taste rate (descending)
fridgeContent.sortByDescending { it.tasteRate }
println(fridgeContent) // [Dish(🧃: 34 cal, taste 4.9/5), Dish(🍨: 207 cal, taste 4.7/5), Dish(🥦: 34 cal, taste 2.3/5)]

val breadBoxContent = mutableListOf(
    Dish("🥯", 245, 4.8f),
    Dish("🥨", 100, 5.0f),
    Dish("🥐", 245, 4.9f)
)

// original order
println(breadBoxContent) // [Dish(🥯: 245 cal, taste 4.8/5), Dish(🥨: 100 cal, taste 5.0/5), Dish(🥐: 245 cal, taste 4.9/5)]

// sort by calories (descending)
breadBoxContent.sortByDescending { it.calories }
// note that the sorting is stable, so the 🥯 is before the 🥐
println(breadBoxContent) // [Dish(🥯: 245 cal, taste 4.8/5), Dish(🥐: 245 cal, taste 4.9/5), Dish(🥨: 100 cal, taste 5.0/5)] 
   //sampleEnd
}

inline fun <T, R : Comparable<R>> MutableList<T>.sortByDescending(crossinline selector: (T) -> R?)

Сортирует элементы списка на месте в порядке убывания согласно естественному порядку сортировки значений, возвращаемых указанной функцией селектора.

Примеры

import kotlin.math.*
import kotlin.test.*

fun main() { 
   //sampleStart 
   class Dish(val name: String, val calories: Int, val tasteRate: Float) {
    override fun toString(): String = "Dish($name: $calories cal, taste $tasteRate/5)"
}

val fridgeContent = mutableListOf(
    Dish("🍨", 207, 4.7f),
    Dish("🥦", 34, 2.3f),
    Dish("🧃", 34, 4.9f)
)

// original order
println(fridgeContent) // [Dish(🍨: 207 cal, taste 4.7/5), Dish(🥦: 34 cal, taste 2.3/5), Dish(🧃: 34 cal, taste 4.9/5)]

// sort by taste rate (descending)
fridgeContent.sortByDescending { it.tasteRate }
println(fridgeContent) // [Dish(🧃: 34 cal, taste 4.9/5), Dish(🍨: 207 cal, taste 4.7/5), Dish(🥦: 34 cal, taste 2.3/5)]

val breadBoxContent = mutableListOf(
    Dish("🥯", 245, 4.8f),
    Dish("🥨", 100, 5.0f),
    Dish("🥐", 245, 4.9f)
)

// original order
println(breadBoxContent) // [Dish(🥯: 245 cal, taste 4.8/5), Dish(🥨: 100 cal, taste 5.0/5), Dish(🥐: 245 cal, taste 4.9/5)]

// sort by calories (descending)
breadBoxContent.sortByDescending { it.calories }
// note that the sorting is stable, so the 🥯 is before the 🥐
println(breadBoxContent) // [Dish(🥯: 245 cal, taste 4.8/5), Dish(🥐: 245 cal, taste 4.9/5), Dish(🥨: 100 cal, taste 5.0/5)] 
   //sampleEnd
}

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Licensed under the Apache License, Version 2.0.
https://kotlinlang.org/api/core/kotlin-stdlib/kotlin.collections/sort-by-descending.html