@ohos.util.Vector (Linear Container Vector)

Vector is a linear data structure that is implemented based on arrays. When the memory of a vector is used up, a larger contiguous memory area is automatically allocated, all the elements are copied to the new memory area, and the current memory area is reclaimed. Vector can be used to efficiently access elements.

Both Vector and ArrayList are implemented based on arrays, but Vector provides more interfaces for operating the arrays. Both of them can dynamically adjust the capacity. Vector doubles the capacity each time, whereas ArrayList increases the capacity by 50%.

Recommended use case: Use Vector when the data volume is large.

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.

The APIs provided by this module are deprecated since API version 9. You are advised to use @ohos.util.ArrayList.

Modules to Import

import Vector from '@ohos.util.Vector';

Vector

Attributes

System capability: SystemCapability.Utils.Lang

constructor

constructor()

A constructor used to create a Vector instance.

System capability: SystemCapability.Utils.Lang

Example

let vector : Vector<string | number | Array<number>> = new Vector();

add

add(element: T): boolean

Adds an element at the end of this container.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

class C1 {
  name: string = ""
  age: string = ""
}
let vector : Vector<string | number | C1 | Array<number>> = new Vector();
let result = vector.add("a");
let result1 = vector.add(1);
let b = [1, 2, 3];
let result2 = vector.add(b);
let c: C1 = {name : "Dylon", age : "13"};
let result3 = vector.add(c);

insert

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

Inserts an element within the length range and moves its subsequent elements rightwards.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let vector : Vector<string | number | Object | Array<number>> = new Vector();
vector.insert("A", 0);
vector.insert(0, 1);
vector.insert(true, 2);

has

has(element: T): boolean

Checks whether this container has the specified element.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let vector : Vector<string> = new Vector();
let result = vector.has("squirrel");
vector.add("squirrel");
let result1 = vector.has("squirrel");

getIndexOf

getIndexOf(element: T): number

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

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

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

getLastIndexOf

getLastIndexOf(element: T): number

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

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

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

removeByIndex

removeByIndex(index: number): T

Searches for an element based on its index, removes the element after returning it, and moves its subsequent elements leftwards.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

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

remove

remove(element: T): boolean

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

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
let result = vector.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.

System capability: SystemCapability.Utils.Lang

Parameters

Example

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

replaceAllElements

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

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

System capability: SystemCapability.Utils.Lang

Parameters

callbackFn

Example

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

forEach

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

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

System capability: SystemCapability.Utils.Lang

Parameters

callbackFn

Example

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

sort

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

Sorts elements in this container.

System capability: SystemCapability.Utils.Lang

Parameters

comparator

Example

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

subVector

subVector(fromIndex: number, toIndex: number): Vector<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 Vector instance.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
vector.add(6);
vector.add(8);
let result = vector.subVector(0,4);
let result1 = vector.subVector(2,4);

clear

clear(): void

Clears all elements in this container and sets its length to 0.

System capability: SystemCapability.Utils.Lang

Example

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

clone

clone(): Vector<T>

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

System capability: SystemCapability.Utils.Lang

Return value

Example

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

getCapacity

getCapacity(): number

Obtains the capacity of this container.

System capability: SystemCapability.Utils.Lang

Return value

Example

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

convertToArray

convertToArray(): Array<T>

Converts this container into an array.

System capability: SystemCapability.Utils.Lang

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
let result = vector.convertToArray();

isEmpty

isEmpty(): boolean

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

System capability: SystemCapability.Utils.Lang

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
let result = vector.isEmpty();

increaseCapacityTo

increaseCapacityTo(newCapacity: number): void

Increases the capacity of this container.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
vector.increaseCapacityTo(2);
vector.increaseCapacityTo(12);

trimToCurrentLength

trimToCurrentLength(): void

Trims the capacity of this container into its current length.

System capability: SystemCapability.Utils.Lang

Example

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

toString

toString(): string

Uses commas (,) to concatenate elements in this container into a string.

System capability: SystemCapability.Utils.Lang

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
let result = vector.toString();

copyToArray

copyToArray(array: Array<T>): void

Copies elements in this container into an array to overwrite elements of the same position indexes.

System capability: SystemCapability.Utils.Lang

Parameters

getFirstElement

getFirstElement(): T

Obtains the first element in this container.

System capability: SystemCapability.Utils.Lang

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
let result = vector.getFirstElement();

getLastElement

getLastElement(): T

Obtains the last element in this container.

System capability: SystemCapability.Utils.Lang

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
let result = vector.getLastElement();

getLastIndexFrom

getLastIndexFrom(element: T, index: number): number

Searches for an element backward from the specified position index and returns the position index of the element.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
let result = vector.getLastIndexFrom(4,3);

getIndexFrom

getIndexFrom(element: T, index: number): number

Searches for an element forward from the specified position index and returns the position index of the element.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
let result = vector.getIndexFrom(4, 3);

setLength

setLength(newSize: number): void

Sets a new length for this container.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
vector.setLength(8);
vector.setLength(2);

get

get(index: number): T

Obtains an element at the specified position in this container.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
let result = vector.get(2);

set

set(index: number, element: T): T

Replaces an element at the specified position in this container with a given element.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

[Symbol.iterator]

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

Obtains an iterator. Each item of the iterator is a JavaScript object.

NOTE

This API cannot be used in .ets files.

System capability: SystemCapability.Utils.Lang

Return value

Example

let vector : Vector<number> = new Vector();
vector.add(2);
vector.add(4);
vector.add(5);
vector.add(4);
// Method 1:
let nums: Array<number> =  vector.convertToArray()
for (let item of nums) {
  console.log("value:" + item);
}

// Method 2:
let iter = vector[Symbol.iterator]();
let temp: IteratorResult<number> = iter.next().value;
while(temp != undefined) {
  console.log("value:" + temp);
  temp = iter.next().value;
}