@ohos.util.ArrayList (Linear Container ArrayList)

ArrayList is a linear data structure that is implemented based on arrays. ArrayList can dynamically adjust the capacity based on project requirements. It increases the capacity by 50% each time.

Similar to ArrayList, Vector is also implemented based on arrays and can dynamically adjust the capacity. It increases the capability by 100% each time.

When compared with LinkedList, ArrayList is more efficient in random access but less efficient in the addition or removal operation, because its addition or removal operation affects the position of other elements in the container.

Recommended use case: Use ArrayList when elements in a container need to be frequently read.

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

T: Type

NOTE

The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

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

ArrayList

Attributes

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

System capability: SystemCapability.Utils.Lang

Name	Type	Readable	Writable	Description
length	number	Yes	No	Number of elements in an array list (called container later).

constructor

constructor()

A constructor used to create an ArrayList instance.

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

System capability: SystemCapability.Utils.Lang

Error codes

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

ID	Error Message
10200012	The ArrayList's constructor cannot be directly invoked.

Example

let arrayList: ArrayList<string|number> = new ArrayList();

add

add(element: T): boolean

Adds an element at the end of this container.

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
element	T	Yes	Target element.

Return value

Type	Description
boolean	Returns true if the element is added successfully; returns false otherwise.

Error codes

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

ID	Error Message
10200011	The add method cannot be bound.

Example

class C1 {
  name: string = ""
  age: string = ""
}
let arrayList: ArrayList<string|number|boolean|Array<number>|C1> = new ArrayList();
let result1 = arrayList.add("a");
let result2 = arrayList.add(1);
let b = [1, 2, 3];
let result3 = arrayList.add(b);
let c : C1 = {name: "Dylan", age: "13"}
let result4 = arrayList.add(c);
let result5 = arrayList.add(false);

insert

insert(element: T, index: number): void

Inserts an element at the specified position in this container.

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
element	T	Yes	Target element.
index	number	Yes	Index of the position where the element is to be inserted. The value must be less than or equal to int32_max, that is, 2147483647.

Error codes

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

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200001	The value of index is out of range.
10200011	The insert method cannot be bound.

Example

let arrayList: ArrayList<number|string|boolean> = new ArrayList();
arrayList.insert("A", 0);
arrayList.insert(0, 1);
arrayList.insert(true, 2);

has

has(element: T): boolean

Checks whether this container has the specified element.

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
element	T	Yes	Target element.

Return value

Type	Description
boolean	Returns true if the specified element is contained; returns false otherwise.

Error codes

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

ID	Error Message
10200011	The has method cannot be bound.

Example

let arrayList: ArrayList<string> = new ArrayList();
arrayList.add("squirrel");
let result: boolean = arrayList.has("squirrel");

getIndexOf

getIndexOf(element: T): number

Obtains the index of the first occurrence of the specified element in this container.

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
element	T	Yes	Target element.

Return value

Type	Description
number	Returns the position index if obtained; returns -1 if the specified element is not found.

Error codes

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

ID	Error Message
10200011	The getIndexOf method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(2);
arrayList.add(1);
arrayList.add(2);
arrayList.add(4);
let result: number = arrayList.getIndexOf(2);

getLastIndexOf

getLastIndexOf(element: T): number

Obtains the index of the last occurrence of the specified element in this container.

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
element	T	Yes	Target element.

Return value

Type	Description
number	Returns the position index if obtained; returns -1 if the specified element is not found.

Error codes

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

ID	Error Message
10200011	The getLastIndexOf method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(2);
arrayList.add(1);
arrayList.add(2);
arrayList.add(4);
let result: number = arrayList.getLastIndexOf(2);

removeByIndex

removeByIndex(index: number): T

Removes an element with the specified position from this container.

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
index	number	Yes	Position index of the target element. The value must be less than or equal to int32_max, that is, 2147483647.

Return value

Type	Description
T	Element removed.

Error codes

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

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200001	The value of index is out of range.
10200011	The removeByIndex method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(2);
arrayList.add(4);
let result: number = arrayList.removeByIndex(2);

remove

remove(element: T): boolean

Removes the first occurrence of the specified element from this container.

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
element	T	Yes	Target element.

Return value

Type	Description
boolean	Returns true if the element is removed successfully; returns false otherwise.

Error codes

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

ID	Error Message
10200011	The remove method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
let result: boolean = arrayList.remove(2);

removeByRange

removeByRange(fromIndex: number, toIndex: number): void

Removes from this container all of the elements within a range, including the element at the start position but not that at the end position.

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
fromIndex	number	Yes	Index of the start position.
toIndex	number	Yes	Index of the end position.

Error codes

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

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200001	The value of fromIndex or toIndex is out of range.
10200011	The removeByRange method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
arrayList.removeByRange(2, 4);

replaceAllElements

replaceAllElements(callbackFn: (value: T, index?: number, arrlist?: ArrayList<T>) => T, thisArg?: Object): void

Replaces all elements in this container with new elements, and returns the new ones.

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
callbackFn	function	Yes	Callback invoked for the replacement.
thisArg	Object	No	Value of this to use when callbackFn is invoked. The default value is this instance.

callbackFn

Name	Type	Mandatory	Description
value	T	Yes	Value of the element that is currently traversed.
index	number	No	Position index of the element that is currently traversed. The default value is 0.
arrlist	ArrayList<T>	No	Instance that calls the replaceAllElements API. The default value is this instance.

Error codes

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

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types.
10200011	The replaceAllElements method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
arrayList.replaceAllElements((value: number): number => {
  // Add the user operation logic based on the actual scenario.
  return value;
});

forEach

forEach(callbackFn: (value: T, index?: number, arrlist?: ArrayList<T>) => void, thisArg?: Object): void

Uses a callback to traverse the elements in this container and obtain their position indexes.

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
callbackFn	function	Yes	Callback invoked for the replacement.
thisArg	Object	No	Value of this to use when callbackFn is invoked. The default value is this instance.

callbackFn

Name	Type	Mandatory	Description
value	T	Yes	Value of the element that is currently traversed.
index	number	No	Position index of the element that is currently traversed. The default value is 0.
arrlist	ArrayList<T>	No	Instance that calls the forEach API. The default value is this instance.

Error codes

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

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types.
10200011	The forEach method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
arrayList.forEach((value: number, index?: number) => {
  console.log("value:" + value, "index:" + index);
});

sort

sort(comparator?: (firstValue: T, secondValue: T) => number): void

Sorts elements in this container.

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
comparator	function	No	Callback invoked for sorting. The default value is the callback function for sorting elements in ascending order.

comparator

Name	Type	Mandatory	Description
firstValue	T	Yes	Previous element.
secondValue	T	Yes	Next element.

Error codes

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

ID	Error Message
401	Parameter error. Possible causes: 1. Incorrect parameter types; 2. Parameter verification failed.
10200011	The sort method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
arrayList.sort((a: number, b: number) => a - b);
arrayList.sort((a: number, b: number) => b - a);
arrayList.sort();

subArrayList

subArrayList(fromIndex: number, toIndex: number): ArrayList<T>

Obtains elements within a range in this container, including the element at the start position but not that at the end position, and returns these elements as a new ArrayList instance.

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
fromIndex	number	Yes	Index of the start position.
toIndex	number	Yes	Index of the end position.

Return value

Type	Description
ArrayList<T>	New ArrayList instance obtained.

Error codes

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

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200001	The value of fromIndex or toIndex is out of range.
10200011	The subArrayList method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
let result: ArrayList<number> = arrayList.subArrayList(2, 4);

clear

clear(): void

Clears this container and sets its length to 0.

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

System capability: SystemCapability.Utils.Lang

Error codes

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

ID	Error Message
10200011	The clear method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
arrayList.clear();

clone

clone(): ArrayList<T>

Clones this container and returns a copy. The modification to the copy does not affect the original instance.

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

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
ArrayList<T>	New ArrayList instance obtained.

Error codes

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

ID	Error Message
10200011	The clone method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
let result:  ArrayList<number> = arrayList.clone();

getCapacity

getCapacity(): number

Obtains the capacity of this container.

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

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
number	Capacity obtained.

Error codes

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

ID	Error Message
10200011	The getCapacity method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
let result: number = arrayList.getCapacity();

convertToArray

convertToArray(): Array<T>

Converts this container into an array.

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

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
Array<T>	Array obtained.

Error codes

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

ID	Error Message
10200011	The convertToArray method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
let result: Array<number> = arrayList.convertToArray();

isEmpty

isEmpty(): boolean

Checks whether this container is empty (contains no element).

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

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
boolean	Returns true if the container is empty; returns false otherwise.

Error codes

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

ID	Error Message
10200011	The isEmpty method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
let result: boolean = arrayList.isEmpty();

[index: number]¹²⁺

[index: number]: T

Returns the element at the given index.

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
index	number	Yes	Index. The value must be less than or equal to int32_max, that is, 2147483647.

Return value

Type	Description
T	Element obtained.

Error codes

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

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

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
let result: number = arrayList[2];

increaseCapacityTo

increaseCapacityTo(newCapacity: number): void

Increases the capacity of this container.

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
newCapacity	number	Yes	New capacity.

Error codes

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

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types.
10200011	The increaseCapacityTo method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
arrayList.increaseCapacityTo(2);
arrayList.increaseCapacityTo(8);

trimToCurrentLength

trimToCurrentLength(): void

Releases the reserved space in this container by adjusting the container capacity to the actual number of elements in this container.

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

System capability: SystemCapability.Utils.Lang

Error codes

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

ID	Error Message
10200011	The trimToCurrentLength method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);
arrayList.trimToCurrentLength();

[Symbol.iterator]

[Symbol.iterator](): IterableIterator<T>

Obtains an iterator, each item of which is a JavaScript object.

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

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
IterableIterator<T>	Iterator obtained.

Error codes

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

ID	Error Message
10200011	The Symbol.iterator method cannot be bound.

Example

let arrayList: ArrayList<number> = new ArrayList();
arrayList.add(2);
arrayList.add(4);
arrayList.add(5);
arrayList.add(4);

// Method 1:
let numbers: Array<number> = arrayList.convertToArray()
for (let item of numbers) {
  console.log(`value : ${item}`);
}

// Method 2:
let iter = arrayList[Symbol.iterator]();
let temp: IteratorResult<number> = iter.next();
while(!temp.done) {
    console.log(`value:${temp.value}`);
    temp = iter.next();
}

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@ohos.util.ArrayList (Linear Container ArrayList)

Modules to Import

ArrayList

Attributes

constructor

add

insert

has

getIndexOf

getLastIndexOf

removeByIndex

remove

removeByRange

replaceAllElements

forEach

sort

subArrayList

clear

clone

getCapacity

convertToArray

isEmpty

[index: number]¹²⁺

increaseCapacityTo

trimToCurrentLength

[Symbol.iterator]

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@ohos.util.ArrayList (Linear Container ArrayList)

Modules to Import

ArrayList

Attributes

constructor

add

insert

has

getIndexOf

getLastIndexOf

removeByIndex

remove

removeByRange

replaceAllElements

forEach

sort

subArrayList

clear

clone

getCapacity

convertToArray

isEmpty

[index: number]12+

increaseCapacityTo

trimToCurrentLength

[Symbol.iterator]

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最热博客

[index: number]¹²⁺