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.
Container classes, implemented in static languages, have restrictions on storage locations and properties, and do not support custom properties or methods.

Specifications

If the value stored in LightWeightSet is of the number type and the value is greater than INT32_MAX or less than INT32_MIN, the operation result of LightWeightSet may be different from the expected result.

This is because the storage structure changes in such cases.

For example, 1758783600000 is greater than INT32_MAX and is stored as TaggedDouble; 1758783600 is less than INT32_MIN and is stored as TaggedInt. Due to these differences in storage modes, the hash algorithm will generate different hash values, leading to inconsistent mapping results and ultimately causing discrepancies from expected outcomes.

let st = new LightWeightSet<number>();
let value = 1758783600000 / 1000;  // 1758783600000 > INT32_MAX
st.add(value);
console.info("result:", st.has(1758783600));  // result: false
console.info("result:", st.has(value));  // result: true

Modules to Import

import { LightWeightSet } from '@kit.ArkTS';

LightWeightSet

[h2]Properties

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Name	Type	Read-Only	Optional	Description
length	number	Yes	No	Number of elements in a LightWeightSet.

[h2]constructor

constructor()

A constructor used to create a LightWeightSet instance.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200012	The LightWeightSet's constructor cannot be directly invoked.

Example

let lightWeightSet = new LightWeightSet<number | string>();

[h2]isEmpty

isEmpty(): boolean

Checks whether this LightWeightSet is empty (contains no element).

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
boolean	Check result. The value true is returned if the LightWeightSet is empty; otherwise, false is returned.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The isEmpty method cannot be bound.

Example

const lightWeightSet = new LightWeightSet<number>();
let result = lightWeightSet.isEmpty();
console.info("result:", result);  // result: true

[h2]add

add(obj: T): boolean

Adds an element to this LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
obj	T	Yes	Target element.

Return value

Type	Description
boolean	Operation result. The value true is returned if the element is added; otherwise, false is returned.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The add method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
let result = lightWeightSet.add("squirrel");
console.info("result:", result);  // result: true

[h2]addAll

addAll(set: LightWeightSet<T>): boolean

Adds all elements in a LightWeightSet to this LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
set	LightWeightSet<T>	Yes	LightWeightSet whose elements are to be added to the current LightWeightSet.

Return value

Type	Description
boolean	Operation result. The value true is returned if the element is added; otherwise, false is returned.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types.
10200011	The addAll method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let set = new LightWeightSet<string>();
set.add("gull");
lightWeightSet.addAll(set);
let result = lightWeightSet.has("gull");
console.info("result:", result);  // result: true

[h2]hasAll

hasAll(set: LightWeightSet<T>): boolean

Checks whether this LightWeightSet contains all elements of the specified LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
set	LightWeightSet<T>	Yes	LightWeightSet instance to be used for comparison.

Return value

Type	Description
boolean	Check result. The value true is returned if all the elements in the specified LightWeightSet are contained; otherwise, false is returned.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types.
10200011	The hasAll method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let set = new LightWeightSet<string>();
set.add("sparrow");
let result = lightWeightSet.hasAll(set);
console.info("result:", result);  // result: true

[h2]has

has(key: T): boolean

Checks whether this LightWeightSet has the specified key.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
key	T	Yes	Target key.

Return value

Type	Description
boolean	Check result. The value true is returned if the specified key is contained; otherwise, false is returned.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The has method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<number>();
lightWeightSet.add(123);
let result = lightWeightSet.has(123);
console.info("result:", result);  // result: true

[h2]increaseCapacityTo

increaseCapacityTo(minimumCapacity: number): void

Increases the capacity of this LightWeightSet. If the passed-in capacity is greater than or equal to the number of elements in this LightWeightSet, the capacity is changed to the new capacity. If the passed-in capacity is less than the number of elements in this LightWeightSet, the capacity is not changed.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
minimumCapacity	number	Yes	Minimum number of elements to accommodate in this LightWeightSet.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types; 3. Parameter verification failed.
10200001	The value of minimumCapacity is out of range.
10200011	The increaseCapacityTo method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.increaseCapacityTo(10);

[h2]getIndexOf

getIndexOf(key: T): number

Obtains the position index of the element with the specified key in this LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
key	T	Yes	Key of the target element.

Return value

Type	Description
number	Position index of the element. If the element does not exist, a negative value is returned. The negative value consists of a minus sign and the position where the element (if available) should be. The position starts from 1.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The getIndexOf method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let result = lightWeightSet.getIndexOf("sparrow");
console.info("result:", result);  // result: 0

[h2]remove

remove(key: T): T

Removes an element of the specified key from this LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
key	T	Yes	Key of the target element.

Return value

Type	Description
T	Value of the element removed.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The remove method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let result = lightWeightSet.remove("sparrow");
console.info("result:", result);  // result: sparrow

[h2]removeAt

removeAt(index: number): boolean

Removes the element at the specified position from this LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
index	number	Yes	Position index of the element. The value must be less than or equal to int32_max, that is, 2147483647.

Return value

Type	Description
boolean	Operation result. The value true is returned if the element is removed; otherwise, false is returned.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types.
10200011	The removeAt method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let result = lightWeightSet.removeAt(1);
console.info("result:", result);  // result: true

[h2]getValueAt

getValueAt(index: number): T

Obtains the value of the element at the specified position in this LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
index	number	Yes	Position index of the element. The value must be less than or equal to int32_max, that is, 2147483647.

Return value

Type	Description
T	Value obtained.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types.
10200011	The getValueAt method cannot be bound.

Parameters

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let result = lightWeightSet.getValueAt(1);
console.info("result:", result);  // result: squirrel

[h2]clear

clear(): void

Clears this LightWeightSet and sets its length to 0.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The clear method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
lightWeightSet.clear();
let result = lightWeightSet.isEmpty();
console.info("result:", result);  // result: true

[h2]toString

toString(): String

Obtains a string that contains all elements in this LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
String	String obtained.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let result = lightWeightSet.toString();
console.info("result:", result);  // result: sparrow,squirrel

[h2]toArray

toArray(): Array<T>

Obtains an array that contains all objects in this LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
Array<T>	Array obtained.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The toArray method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let result = lightWeightSet.toArray();

[h2]values

values(): IterableIterator<T>

Returns an iterator that contains all the values in this LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
IterableIterator<T>	Iterator obtained.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The values method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let values = lightWeightSet.values();
for (let value of values) {
  console.info("value:", value);
}
// value: sparrow
// value: squirrel

[h2]forEach

forEach(callbackFn: (value?: T, key?: T, set?: LightWeightSet<T>) => void, thisArg?: Object): void

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

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
callbackFn	function	Yes	Callback invoked to traverse the elements in the LightWeightSet.
thisArg	Object	No	Value of this to use when callbackFn is invoked. The default value is this instance.

callbackFn parameters

Name	Type	Mandatory	Description
value	T	No	Value of the element that is currently traversed. The default value is the value of the first key-value pair.
key	T	No	Key of the element that is currently traversed (same as value). The default value is the key of the first key-value pair.
set	LightWeightSet<T>	No	Instance that calls the forEach API. The default value is this instance.

Error codes

For details about the error codes, see Universal Error Codes and Utils Error Codes.

ID	Error Message
401	Parameter error. Possible causes: 1. Mandatory parameters are left unspecified; 2. Incorrect parameter types.
10200011	The forEach method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("sparrow");
lightWeightSet.add("gull");
lightWeightSet.forEach((value: string, key: string) => {
  console.info("value:" + value, "key:" + key);
});
// value:gull key:gull
// value:sparrow key:sparrow

// You are not advised to use the add, remove, or removeAt APIs in forEach because they may cause unpredictable risks such as infinite loops. You can use the for loop when inserting or deleting data.
let lightWeightSet = new LightWeightSet<string>();
for(let i = 0; i < 10; i++) {
  lightWeightSet.add(i + "123");
}
for(let i = 0; i < 10; i++) {
  lightWeightSet.remove(i + "123");
}

[h2]entries

entries(): IterableIterator<[T, T]>

Returns an iterator that contains all the elements in this LightWeightSet.

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
IterableIterator<[T, T]>	Iterator obtained.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The entries method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let iter = lightWeightSet.entries();
for (let item of iter) {
  console.info("value:", item[1])
}
// value: sparrow
// value: squirrel

// You are not advised to use the add, remove, or removeAt APIs in entries because they may cause unpredictable risks such as infinite loops. You can use the for loop when inserting or deleting data.
let lightWeightSet = new LightWeightSet<string>();
for(let i = 0; i < 10; i++) {
  lightWeightSet.add(i + "123");
}
for(let i = 0; i < 10; i++) {
  lightWeightSet.remove(i + "123");
}

[h2][Symbol.iterator]

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

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

Atomic service API: This API can be used in atomic services since API version 12.

System capability: SystemCapability.Utils.Lang

Return value

Type	Description
IterableIterator<T>	Iterator obtained.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The Symbol.iterator method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");

// Method 1:
for (let value of lightWeightSet) {
  console.info("value:", value);
}
// value: sparrow
// value: squirrel

// Method 2:
let iter = lightWeightSet[Symbol.iterator]();
let temp: IteratorResult<string> = iter.next();
while(!temp.done) {
  console.info("value:", temp.value);
  temp = iter.next();
}
// value: sparrow
// value: squirrel

// You are not advised to use the add, remove, or removeAt APIs in Symbol.iterator because they may cause unpredictable risks such as infinite loops. You can use the for loop when inserting or deleting data.
let lightWeightSet = new LightWeightSet<string>();
for(let i = 0; i < 10; i++) {
  lightWeightSet.add(i + "123");
}
for(let i = 0; i < 10; i++) {
  lightWeightSet.remove(i + "123");
}

[h2]equal^(deprecated)

equal(obj: Object): boolean

Checks whether the elements of this LightWeightSet are the same as those of obj.

This API is supported since API version 8 and deprecated since API version 12. There is no substitute API.

System capability: SystemCapability.Utils.Lang

Parameters

Name	Type	Mandatory	Description
obj	Object	Yes	LightWeightSet instance to be used for comparison.

Return value

Type	Description
boolean	Returns true if obj is a LightWeightSet or an array containing only strings or numbers and the elements in them are the same; returns false in other cases.

Error codes

For details about the error codes, see Utils Error Codes.

ID	Error Message
10200011	The equal method cannot be bound.

Example

let lightWeightSet = new LightWeightSet<string>();
lightWeightSet.add("squirrel");
lightWeightSet.add("sparrow");
let obj = ["sparrow", "squirrel"];
let result = lightWeightSet.equal(obj);
console.info("result:", result);  // result: true

目录

@ohos.util.LightWeightSet (Nonlinear Container LightWeightSet)

Specifications

Modules to Import

LightWeightSet

[h2]Properties

[h2]constructor

[h2]isEmpty

[h2]add

[h2]addAll

[h2]hasAll

[h2]has

[h2]increaseCapacityTo

[h2]getIndexOf

[h2]remove

[h2]removeAt

[h2]getValueAt

[h2]clear

[h2]toString

[h2]toArray

[h2]values

[h2]forEach

[h2]entries

[h2][Symbol.iterator]

[h2]equal^(deprecated)

目录

@ohos.util.LightWeightSet (Nonlinear Container LightWeightSet)

Specifications

Modules to Import

LightWeightSet

[h2]Properties

[h2]constructor

[h2]isEmpty

[h2]add

[h2]addAll

[h2]hasAll

[h2]has

[h2]increaseCapacityTo

[h2]getIndexOf

[h2]remove

[h2]removeAt

[h2]getValueAt

[h2]clear

[h2]toString

[h2]toArray

[h2]values

[h2]forEach

[h2]entries

[h2][Symbol.iterator]

[h2]equal(deprecated)

[h2]equal^(deprecated)