Linear Container List

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 List from '@ohos.util.List';  

System Capabilities

SystemCapability.Utils.Lang

List

Attributes

constructor

constructor()

A constructor used to create a List instance.

Example

let list = new List();

add

add(element: T): boolean

Adds an entry at the end of this container.

Parameters

Return value

Example

let list = new List();
let result = list.add("a");
let result1 = list.add(1);
let b = [1, 2, 3];
list.add(b);
let c = {name : "lala", age : "13"};
let result3 = list.add(false);

insert

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

Inserts an entry at the specified position in this container.

Parameters

Example

let list = new List();
list.insert("A", 0);
list.insert(0, 1);
list.insert(true, 2);

has

has(element: T): boolean

Checks whether this container has the specified entry.

Parameters

Return value

Example

let list = new List();
let result = list.has("Ahfbrgrbgnutfodgorrogorg");
list.add("Ahfbrgrbgnutfodgorrogorg");
let result1 = list.has("Ahfbrgrbgnutfodgorrogorg");

get

get(index: number): T

Obtains the entry at the specified position in this container.

Parameters

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(2);
list.add(1);
list.add(2);
list.add(4);
let result = list.get(2);

getLastIndexOf

getLastIndexOf(element: T): number

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

Parameters

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(2);
list.add(1);
list.add(2);
list.add(4);
let result = list.getLastIndexOf(2);

getIndexOf

getIndexOf(element: T): number

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

Parameters

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(2);
list.add(1);
list.add(2);
list.add(4);
list.getIndexOf(2);
let result = list.getIndexOf(2);

equal

equal(obj: Object): boolean

Compares whether a specified object is equal to this container.

Parameters

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(2);
let obj1 = new List();
obj1.add(2);
obj1.add(4);
obj1.add(5);
list.equal(obj1);
let obj2 = {name : "lala", age : "13"};
let result = list.equal(obj2);

removeByIndex

removeByIndex(index: number): T

Removes an entry at the specified position from this container.

Parameters

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(2);
list.add(4);
let result = list.removeByIndex(2);

remove

remove(element: T): boolean

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

Parameters

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
let result = list.remove(2);

replaceAllElements

replaceAllElements(callbackfn: (value: T, index?: number, list?: List<T>) => T, thisArg?: Object): void

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

Parameters

callbackfn

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
list.replaceAllElements((value, index) => {
  return value = 2 * value;
});
list.replaceAllElements((value, index) => {
  return value = value - 2;
});

forEach

forEach(callbackfn: (value: T, index?: number, List?: List<T>) => void, thisArg?: Object): void

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

Parameters

callbackfn

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
list.forEach((value, index) => {
  console.log("value: " + value, index);
});

sort

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

Sorts entries in this container.

Parameters

comparator

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
list.sort((a, b) => a - b);
list.sort((a, b) => b - a);

getSubList

getSubList(fromIndex: number, toIndex: number): List<T>

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

Parameters

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
let result = list.subList(2, 4);
let result1 = list.subList(4, 3);
let result2 = list.subList(2, 6);

clear

clear(): void

Clears this container and sets its length to 0.

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
list.clear();

set

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

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

Parameters

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
list.set(2, "b");

convertToArray

convertToArray(): Array<T>

Converts this container into an array.

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
let result = list.convertToArray();

isEmpty

isEmpty(): boolean

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

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
let result = list.isEmpty();

getFirst

getFirst(): T

Obtains the first entry in this container.

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
let result = list.getFirst();

getLast

getLast(): T

Obtains the last entry in this container.

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);
let result = list.getLast();

[Symbol.iterator]

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

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

Return value

Example

let list = new List();
list.add(2);
list.add(4);
list.add(5);
list.add(4);

// Method 1:
for (let item of list) { 
  console.log("value: " + item); 
}

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