Nonlinear Container LightWeightMap

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 LightWeightMap from '@ohos.util.LightWeightMap';

System Capabilities

SystemCapability.Utils.Lang

LightWeightMap

Attributes

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

constructor

constructor()

A constructor used to create a LightWeightMap instance.

Example

let lightWeightMap = new LightWeightMap();

isEmpty

isEmpty(): boolean

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

Return value

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

Example

const lightWeightMap = new LightWeightMap();
let result = lightWeightMap.isEmpty();

hasAll

hasAll(map: LightWeightMap<K, V>): boolean

Checks whether this container contains all entries of the specified LightWeightMap instance.

Parameters

Name Type Mandatory Description
map LightWeightMap<K, V> Yes LightWeightMap instance to be used for comparison.

Return value

Type Description
boolean Returns true if all the entries in the specified LightWeightMap instance are contained; returns false otherwise.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let map = new LightWeightMap();
map.set("sdfs", 356);
let result = lightWeightMap.hasAll(map);

hasKey

hasKey(key: K): boolean;

Checks whether this container contains the specified key.

Parameters

Name Type Mandatory Description
key K Yes Key to check.

Return value

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

Example

let lightWeightMap = new LightWeightMap();
let result = lightWeightMap.hasKey;
lightWeightMap.hasKey("Ahfbrgrbgnutfodgorrogorgrogofdfdf");
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
let result1 = lightWeightMap.hasKey("Ahfbrgrbgnutfodgorrogorgrogofdfdf");

hasValue

hasValue(value: V): boolean

Checks whether this container contains the specified value.

Parameters

Name Type Mandatory Description
value V Yes Value to check.

Return value

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

Example

let lightWeightMap = new LightWeightMap();
let result = lightWeightMap.hasValue(123);
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
let result1 = lightWeightMap.hasValue(123);

increaseCapacityTo

increaseCapacityTo(minimumCapacity: number): void

Increases the capacity of this container.

Parameters

Name Type Mandatory Description
minimumCapacity number Yes Minimum number of entries to accommodate in this container.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.increaseCapacityTo(10);

get

get(key: K): V

Obtains the value of the specified key in this container.

Parameters

Name Type Mandatory Description
key K Yes Key to query.

Return value

Type Description
V Value of the key.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let result = lightWeightMap.get("sdfs");

getIndexOfKey

getIndexOfKey(key: K): number

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

Parameters

Name Type Mandatory Description
key K Yes Key of the entry.

Return value

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

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let result = lightWeightMap.getIndexOfKey("sdfs");

getIndexOfValue

getIndexOfValue(value: V): number

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

Parameters

Name Type Mandatory Description
value V Yes Value of the entry.

Return value

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

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let result = lightWeightMap.getIndexOfValue(123);

getKeyAt

getKeyAt(index: number): K

Obtains the key of an entry at the specified position in this container.

Parameters

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

Return value

Type Description
K Returns the key if obtained; returns undefined otherwise.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let result = lightWeightMap.getKeyAt(1);

setAll

setAll(map: LightWeightMap<K, V>): void

Adds all entries in a LightWeightMap instance to this container.

Parameters

Name Type Mandatory Description
map LightWeightMap<K, V> Yes LightWeightMap instance whose entries are to be added to the current container.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let map = new LightWeightMap();
lightWeightMap.setAll(map);

set

set(key: K, value: V): Object

Adds an entry to this container.

Parameters

Name Type Mandatory Description
key K Yes Key of the entry to add.
value V Yes Value of the entry to add.

Return value

Type Description
Object Container that contains the new entry.

Example

let lightWeightMap = new LightWeightMap();
let result = lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);

remove

remove(key: K): V

Removes an entry with the specified key from this container.

Parameters

Name Type Mandatory Description
key K Yes Key of the entry to remove.

Return value

Type Description
V Value of the entry removed.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
lightWeightMap.remove("sdfs");

removeAt

removeAt(index: number): boolean

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

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let result = lightWeightMap.removeAt(1);

setValueAt

setValueAt(index: number, newValue: V): boolean

Sets a value for an entry at the specified position in this container.

Parameters

Name Type Mandatory Description
index number Yes Position index of the entry.
newValue V Yes Value of the entry to set.

Return value

Type Description
boolean Returns true if the value is set successfully; returns false otherwise.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
lightWeightMap.setValueAt(1, 3546);

getValueAt

getValueAt(index: number): V

Obtains the value of an entry at the specified position in this container.

Parameters

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

Return value

Type Description
V Value obtained.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let result = lightWeightMap.getValueAt(1);

clear

clear(): void

Clears this container and sets its length to 0.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
lightWeightMap.clear();

keys

keys(): IterableIterator<K>

Obtains an iterator that contains all the keys in this container.

Return value

Type Description
IterableIterator<K> Iterator obtained.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let iter = lightWeightMap.keys();
let temp = iter.next().value;
while(temp != undefined) {
  console.log("value:" + temp);
  temp = iter.next().value;
}

values

values(): IterableIterator<V>

Obtains an iterator that contains all the values in this container.

Return value

Type Description
IterableIterator<V> Iterator obtained.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let iter = lightWeightMap.values();
let temp = iter.next().value;
while(temp != undefined) {
  console.log("value:" + temp);
  temp = iter.next().value;
}

forEach

forEach(callbackfn: (value?: V, key?: K, map?: LightWeightMap<K, V>) => 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 V No Value of the entry that is currently traversed.
key K No Key of the entry that is currently traversed.
map LightWeightMap<K, V> No Instance that invokes the forEach method.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("sdfs", 123);
lightWeightMap.set("dfsghsf", 357);
lightWeightMap.forEach((value, key) => {
  console.log("value:" + value, key);
});

entries

entries(): IterableIterator<[K, V]>

Obtains an iterator that contains all the entries in this container.

Return value

Type Description
IterableIterator<[K, V]> Iterator obtained.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);
let iter = lightWeightMap.entries();
let temp = iter.next().value;
while(temp != undefined) {
  console.log("key:" + temp[0]);
  console.log("value:" + temp[1]);
  temp = iter.next().value;
}

toString

toString(): String

Concatenates the entries in this container into a string and returns the string.

Return value

Type Description
String Returns a string.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("A", 123);
lightWeightMap.set("sdfs", 356);
let iter = lightWeightMap.toString();

[Symbol.iterator]

[Symbol.iterator](): IterableIterator<[K, V]>

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

Return value

Type Description
IterableIterator<[K, V]> Iterator obtained.

Example

let lightWeightMap = new LightWeightMap();
lightWeightMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
lightWeightMap.set("sdfs", 356);

// Method 1:
for (let item of lightWeightMap) { 
  console.log("key:" + item[0]);
  console.log("value:" + item[1]);
}

// Method 2:
let iter = lightWeightMap[Symbol.iterator]();
let temp = iter.next().value;
while(temp != undefined) {
  console.log("key:" + temp[0]);
  console.log("value:" + temp[1]);
  temp = iter.next().value;
}