Linear Container LinkedList

icon-note.gif 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 LinkedList from '@ohos.util.LinkedList';

System Capability

SystemCapability.Utils.Lang

LinkedList

Attributes

Name Type Readable Writable Description
length number Yes No Number of entries in a linked list (called container later).

constructor

constructor()

A constructor used to create a LinkedList instance.

Example

let linkedList = new LinkedList();

add

add(element: T): boolean

Adds an entry at the end of this container.

Parameters

Name Type Mandatory Description
element T Yes Entry to add.

Return value

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

Example

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

addFirst

addFirst(element: T): void

Adds an entry at the top of this container.

Parameters

Name Type Mandatory Description
element T Yes Entry to add.

Example

let linkedList = new LinkedList();
linkedList.addFirst("a");
linkedList.addFirst(1);
let b = [1, 2, 3];
linkedList.addFirst(b);
let c = {name : "lala", age : "13"};
linkedList.addFirst(false);

insert

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

Inserts an entry at the specified position in this container.

Parameters

Name Type Mandatory Description
element T Yes Entry to insert.
index number Yes Index of the position where the entry is to be inserted.

Example

let linkedList = new LinkedList();
linkedList.insert(0, "A");
linkedList.insert(1, 0);
linkedList.insert(2, true);

has

has(element: T): boolean

Checks whether this container has the specified entry.

Parameters

Name Type Mandatory Description
element T Yes Entry to check.

Return value

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

Example

let linkedList = new LinkedList();
let result1 = linkedList.has("Ahfbrgrbgnutfodgorrogorg");
linkedList.add("Ahfbrgrbgnutfodgorrogorg");
let result = linkedList.has("Ahfbrgrbgnutfodgorrogorg");

get

get(index: number): T

Obtains an entry at the specified position in this container.

Parameters

Name Type Mandatory Description
index number Yes Position index of the entry to query.

Return value

Type Description
T Entry obtained.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(2);
linkedList.add(1);
linkedList.add(2);
linkedList.add(4);
let result = linkedList.get(2);

getLastIndexOf

getLastIndexOf(element: T): number

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

Parameters

Name Type Mandatory Description
element T Yes Entry to check.

Return value

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

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(2);
linkedList.add(1);
linkedList.add(2);
linkedList.add(4);
let result = linkedList.getLastIndexOf(2);

getIndexOf

getIndexOf(element: T): number

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

Parameters

Name Type Mandatory Description
element T Yes Entry to check.

Return value

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

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(2);
linkedList.add(1);
linkedList.add(2);
linkedList.add(4);
let result = linkedList.getIndexOf(2);

removeByIndex

removeByIndex(index: number): T

Removes an entry at the specified position from this container.

Parameters

Name Type Mandatory Description
index number Yes Position index of the entry to remove.

Return value

Type Description
T Entry removed.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(2);
linkedList.add(4);
let result = linkedList.removeByIndex(2);

removeFirst

removeFirst(): T

Removes the first entry from this container.

Return value

Type Description
T Entry removed.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(2);
linkedList.add(4);
let result = linkedList.removeFirst();

removeLast

removeLast(): T

Removes the last entry from this container.

Return value

Type Description
T Entry removed.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(2);
linkedList.add(4);
let result = linkedList.removeLast();

remove

remove(element: T): boolean

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

Parameters

Name Type Mandatory Description
element T Yes Entry to check.

Return value

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

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(4);
let result = linkedList.remove(2);

removeFirstFound

removeFirstFound(element: T): boolean

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

Parameters

Name Type Mandatory Description
element T Yes Entry to check.

Return value

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

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(4);
let result = linkedList.removeFirstFound(4);

removeLastFound

removeLastFound(element: T): boolean

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

Parameters

Name Type Mandatory Description
element T Yes Entry to check.

Return value

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

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(4);
let result = linkedList.removeLastFound(4);

clone

clone(): LinkedList<T>

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

Return value

Type Description
LinkedList<T> New LinkedList instance obtained.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(4);
let result = linkedList.clone();

forEach

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

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

Parameters

Name Type Mandatory Description
callbackfn function Yes Callback invoked to traverse the entries in the container.
thisArg Object No Value to use when the callback is invoked.

callbackfn

Name Type Mandatory Description
value T Yes Value of the entry that is currently traversed.
index number No Position index of the entry that is currently traversed.
LinkedList LinkedList<T> No Instance that invokes the forEach API.

Example

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

clear

clear(): void

Clears this container and sets its length to 0.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(4);
linkedList.clear();

set

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

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

Parameters

Name Type Mandatory Description
index number Yes Position index of the entry to replace.
element T Yes Entry to be used for replacement.

Return value

Type Description
T New entry.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(4);
let result = linkedList.set(2, "b");

convertToArray

convertToArray(): Array<T>

Converts this container into an array.

Return value

Type Description
Array<T> Array obtained.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(4);
let result = linkedList.convertToArray();

getFirst

getFirst(): T

Obtains the first entry in this container.

Return value

Type Description
T Returns the entry if obtained; returns undefined otherwise.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(4);
let result = linkedList.getFirst();

getLast

getLast(): T

Obtains the last entry in this container.

Return value

Type Description
T Returns the entry if obtained; returns undefined otherwise.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(4);
linkedList.getLast();

[Symbol.iterator]

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

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

Return value

Type Description
IterableIterator<T> Iterator obtained.

Example

let linkedList = new LinkedList();
linkedList.add(2);
linkedList.add(4);
linkedList.add(5);
linkedList.add(4);

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

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