Kotlin массив из объектов

Array

Represents an array (specifically, a Java array when targeting the JVM platform). Array instances can be created using the arrayOf, arrayOfNulls and emptyArray standard library functions. See Kotlin language documentation for more information on arrays.

For Native

Represents an array. Array instances can be created using the constructor, arrayOf, arrayOfNulls and emptyArray standard library functions. See Kotlin language documentation for more information on arrays.

Constructors

Creates a new array with the specified size, where each element is calculated by calling the specified init function.

Properties

size

Returns the number of elements in the array.

Functions

get

Returns the array element at the specified index. This method can be called using the index operator.

iterator

Creates an Iterator for iterating over the elements of the array.

set

Sets the array element at the specified index to the specified value. This method can be called using the index operator.

Extension Properties

indices

Returns the range of valid indices for the array.

lastIndex

Returns the last valid index for the array.

Extension Functions

all

Returns true if all elements match the given predicate.

any

Returns true if array has at least one element.

Returns true if at least one element matches the given predicate.

asIterable

Creates an Iterable instance that wraps the original array returning its elements when being iterated.

asSequence

Creates a Sequence instance that wraps the original array returning its elements when being iterated.

associate

Returns a Map containing key-value pairs provided by transform function applied to elements of the given array.

associateBy

Returns a Map containing the elements from the given array indexed by the key returned from keySelector function applied to each element.

Returns a Map containing the values provided by valueTransform and indexed by keySelector functions applied to elements of the given array.

associateByTo

Populates and returns the destination mutable map with key-value pairs, where key is provided by the keySelector function applied to each element of the given array and value is the element itself.

Populates and returns the destination mutable map with key-value pairs, where key is provided by the keySelector function and and value is provided by the valueTransform function applied to elements of the given array.

fun < T , K , V , M : MutableMap < in K , in V >> Array < out T >. associateByTo (
destination : M ,
keySelector : ( T ) -> K ,
valueTransform : ( T ) -> V
) : M

associateTo

Populates and returns the destination mutable map with key-value pairs provided by transform function applied to each element of the given array.

associateWith

Returns a Map where keys are elements from the given array and values are produced by the valueSelector function applied to each element.

associateWithTo

Populates and returns the destination mutable map with key-value pairs for each element of the given array, where key is the element itself and value is provided by the valueSelector function applied to that key.

average

Returns an average value of elements in the array.

binarySearch

Searches the array or the range of the array for the provided element using the binary search algorithm. The array is expected to be sorted according to the specified comparator, otherwise the result is undefined.

fun < T >Array < out T >. binarySearch (
element : T ,
comparator : Comparator < in T >,
fromIndex : Int = 0 ,
toIndex : Int = size
) : Int

Searches the array or the range of the array for the provided element using the binary search algorithm. The array is expected to be sorted, otherwise the result is undefined.

component1

Returns 1st element from the array.

component2

Returns 2nd element from the array.

component3

Returns 3rd element from the array.

component4

Returns 4th element from the array.

component5

Returns 5th element from the array.

contains

Returns true if element is found in the array.

contentEquals

Returns true if the two specified arrays are structurally equal to one another, i.e. contain the same number of the same elements in the same order.

contentHashCode

Returns a hash code based on the contents of this array as if it is List.

contentToString

Returns a string representation of the contents of the specified array as if it is List.

count

Returns the number of elements in this array.

Returns the number of elements matching the given predicate.

distinct

Returns a list containing only distinct elements from the given array.

distinctBy

Returns a list containing only elements from the given array having distinct keys returned by the given selector function.

drop

Returns a list containing all elements except first n elements.

dropLast

Returns a list containing all elements except last n elements.

dropLastWhile

Returns a list containing all elements except last elements that satisfy the given predicate.

dropWhile

Returns a list containing all elements except first elements that satisfy the given predicate.

elementAtOrElse

Returns an element at the given index or the result of calling the defaultValue function if the index is out of bounds of this array.

elementAtOrNull

Returns an element at the given index or null if the index is out of bounds of this array.

filter

Returns a list containing only elements matching the given predicate.

filterIndexed

Returns a list containing only elements matching the given predicate.

filterIndexedTo

Appends all elements matching the given predicate to the given destination.

fun < T , C : MutableCollection < in T >> Array < out T >. filterIndexedTo (
destination : C ,
predicate : ( index : Int , T ) -> Boolean
) : C

filterIsInstance

Returns a list containing all elements that are instances of specified type parameter R.

Returns a list containing all elements that are instances of specified class.

filterIsInstanceTo

Appends all elements that are instances of specified type parameter R to the given destination.

Appends all elements that are instances of specified class to the given destination.

filterNot

Returns a list containing all elements not matching the given predicate.

filterNotNull

Returns a list containing all elements that are not null .

filterNotNullTo

Appends all elements that are not null to the given destination.

filterNotTo

Appends all elements not matching the given predicate to the given destination.

filterTo

Appends all elements matching the given predicate to the given destination.

find

Returns the first element matching the given predicate, or null if no such element was found.

findLast

Returns the last element matching the given predicate, or null if no such element was found.

first

Returns the first element.

Returns the first element matching the given predicate.

firstNotNullOf

Returns the first non-null value produced by transform function being applied to elements of this array in iteration order, or throws NoSuchElementException if no non-null value was produced.

firstNotNullOfOrNull

Returns the first non-null value produced by transform function being applied to elements of this array in iteration order, or null if no non-null value was produced.

firstOrNull

Returns the first element, or null if the array is empty.

Returns the first element matching the given predicate, or null if element was not found.

flatMap

Returns a single list of all elements yielded from results of transform function being invoked on each element of original array.

flatMapIndexed

Returns a single list of all elements yielded from results of transform function being invoked on each element and its index in the original array.

flatMapIndexedTo

Appends all elements yielded from results of transform function being invoked on each element and its index in the original array, to the given destination.

fun < T , R , C : MutableCollection < in R >> any_array . flatMapIndexedTo (
destination : C ,
transform : ( index : Int , T ) -> Iterable < R >
) : C

flatMapTo

Appends all elements yielded from results of transform function being invoked on each element of original array, to the given destination.

fun < T , R , C : MutableCollection < in R >> any_array . flatMapTo (
destination : C ,
transform : ( T ) -> Iterable < R >
) : C

flatten

Returns a single list of all elements from all arrays in the given array.

fold

Accumulates value starting with initial value and applying operation from left to right to current accumulator value and each element.

foldIndexed

Accumulates value starting with initial value and applying operation from left to right to current accumulator value and each element with its index in the original array.

foldRight

Accumulates value starting with initial value and applying operation from right to left to each element and current accumulator value.

foldRightIndexed

Accumulates value starting with initial value and applying operation from right to left to each element with its index in the original array and current accumulator value.

forEach

Performs the given action on each element.

forEachIndexed

Performs the given action on each element, providing sequential index with the element.

getOrElse

Returns an element at the given index or the result of calling the defaultValue function if the index is out of bounds of this array.

getOrNull

Returns an element at the given index or null if the index is out of bounds of this array.

groupBy

Groups elements of the original array by the key returned by the given keySelector function applied to each element and returns a map where each group key is associated with a list of corresponding elements.

Groups values returned by the valueTransform function applied to each element of the original array by the key returned by the given keySelector function applied to the element and returns a map where each group key is associated with a list of corresponding values.

groupByTo

Groups elements of the original array by the key returned by the given keySelector function applied to each element and puts to the destination map each group key associated with a list of corresponding elements.

Groups values returned by the valueTransform function applied to each element of the original array by the key returned by the given keySelector function applied to the element and puts to the destination map each group key associated with a list of corresponding values.

fun < T , K , V , M : MutableMap < in K , MutableList < V >> > Array < out T >. groupByTo (
destination : M ,
keySelector : ( T ) -> K ,
valueTransform : ( T ) -> V
) : M

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Arrays

Arrays in Kotlin are represented by the Array class. It has get() and set() functions that turn into [] by operator overloading conventions, and the size property, along with other useful member functions:

To create an array, use the function arrayOf() and pass the item values to it, so that arrayOf(1, 2, 3) creates an array [1, 2, 3] . Alternatively, the arrayOfNulls() function can be used to create an array of a given size filled with null elements.

Another option is to use the Array constructor that takes the array size and the function that returns values of array elements given its index:

The [] operation stands for calls to member functions get() and set() .

Arrays in Kotlin are invariant. This means that Kotlin does not let us assign an Array to an Array , which prevents a possible runtime failure (but you can use Array , see Type Projections).

Primitive type arrays

Kotlin also has classes that represent arrays of primitive types without boxing overhead: ByteArray , ShortArray , IntArray , and so on. These classes have no inheritance relation to the Array class, but they have the same set of methods and properties. Each of them also has a corresponding factory function:

// Array of int of size 5 with values [0, 0, 0, 0, 0] val arr = IntArray(5) // Example of initializing the values in the array with a constant // Array of int of size 5 with values [42, 42, 42, 42, 42] val arr = IntArray(5) < 42 >// Example of initializing the values in the array using a lambda // Array of int of size 5 with values [0, 1, 2, 3, 4] (values initialized to their index value) var arr = IntArray(5) < it * 1 >

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