Interface (ConcatArray)

An array-like object that can be concatenated. This API extends ISendable.

NOTE

The initial APIs of this module are supported since API version 12. Newly added APIs will be marked with a superscript to indicate their earliest API version.

This module can be imported only to ArkTS files (with the file name extension .ets).

This section uses the following to identify the use of generics:

T: type, which can be any of the sendable data types.

Modules to Import

import { collections } from '@kit.ArkTS';

Properties

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Name	Type	Read Only	Optional	Description
length	number	Yes	No	Number of elements in a ConcatArray.

[index: number]

readonly [index: number]: T

Returns the element at a given index in this ConcatArray.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
index	number	Yes	Index of the element. The index starts from zero. The element at the specified index cannot be modified.

Return value

Type	Description
T	Element in the ConcatArray.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Illegal index.
10200001	The value of index is out of range.

Example

let concatArray : collections.ConcatArray<number> = new collections.Array<number>(1, 2, 4);
console.info("Element at index 1: ", concatArray[1]);

join

join(separator?: string): string

Concatenates all elements in this array into a string, with a given separator.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
separator	string	No	Separator to be used. If no value is passed in, a comma (,) is used as the separator.

Return value

Type	Description
string	String obtained. If the array is empty, an empty string is returned.

Error codes

For details about the error codes, see Universal Error Codes.

ID	Error Message
401	Parameter error. Invalid separator.

Example

let concatArray : collections.ConcatArray<string> = new collections.Array<string>('a', 'b', 'c');
let joinedString = concatArray.join('-'); // "a-b-c" is returned.

slice

slice(start?: number, end?: number): ConcatArray<T>

Selects a range of elements in this array to create an array.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
start	number	No	Start index of the range. If a negative number is passed in, it refers to the index of `start + array.length`. The default value is 0.
end	number	No	End index of the range (exclusive). If a negative number is passed in, it refers to the index of `end + array.length`. The default value is the length of the ArkTS array.

Return value

Type	Description
ConcatArray<T>	New array containing the selected elements.

Error codes

For details about the error codes, see Universal Error Codes.

ID	Error Message
401	Parameter error. Invalid `start` or `end` parameters.

Example

let concatArray : collections.ConcatArray<number> = new collections.Array<number>(1, 2, 3, 4, 5);
let slicedArray = concatArray.slice (1, 3); // [2, 3] is returned. The original array remains unchanged.