Nonlinear Container HashMap

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 HashMap from '@ohos.util.HashMap';

System Capabilities

SystemCapability.Utils.Lang

HashMap

Attributes

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

constructor

constructor()

A constructor used to create a HashMap instance.

Example

let hashMap = new HashMap();

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 hashMap = new HashMap();
let result = hashMap.isEmpty();

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 hashMap = new HashMap();
let result = hashMap.hasKey("Ahfbrgrbgnutfodgorrogorgrogofdfdf");
hashMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
let result1 = hashMap.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 hashMap = new HashMap();
let result = hashMap.hasValue(123);
hashMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
let result1 = hashMap.hasValue(123);

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 obtained.

Example

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

setAll

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

Adds all entries in a HashMap instance to this container.

Parameters

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

Example

let hashMap = new HashMap();
hashMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
hashMap.set("sdfs", 356);
let newHashMap = new HashMap();
hashMap.setAll(newHashMap);

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 hashMap = new HashMap();
let result = hashMap.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 hashMap = new HashMap();
hashMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
hashMap.set("sdfs", 356);
let result = hashMap.remove("sdfs");

clear

clear(): void

Clears this container and sets its length to 0.

Example

let hashMap = new HashMap();
hashMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
hashMap.set("sdfs", 356);
hashMap.clear();

keys

keys(): IterableIterator<K>

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

Return value

Type Description
IterableIterator<K> Iterator obtained.

Example

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

replace

replace(key: K, newValue: V): boolean

Replaces an entry in this container.

Parameters

Name Type Mandatory Description
key K Yes Key of the entry to replace.
newValue V Yes New value of the entry.

Return value

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

Example

let hashMap = new HashMap();
hashMap.set("sdfs", 123);
let result = hashMap.replace("sdfs", 357);

forEach

forEach(callbackfn: (value?: V, key?: K, map?: HashMap<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 HashMap<K, V> No Instance that invokes the forEach method.

Example

let hashMap = new HashMap();
hashMap.set("sdfs", 123);
hashMap.set("dfsghsf", 357);
hashMap.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 hashMap = new HashMap();
hashMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
hashMap.set("sdfs", 356);
let iter = hashMap.entries();
let temp = iter.next().value;
while(temp != undefined) {
  console.log("key:" + temp[0]);
  console.log("value:" + temp[1]);
  temp = iter.next().value;
}

[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 hashMap = new HashMap();
hashMap.set("Ahfbrgrbgnutfodgorrogorgrogofdfdf", 123);
hashMap.set("sdfs", 356);

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

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