@ohos.util (util)

The util module provides common utility functions, such as TextEncoder and TextDecoder for string encoding and decoding, RationalNumber⁸⁺ for rational number operations, LRUCache⁹⁺ for cache management, ScopeHelper⁹⁺ for range determination, Base64Helper⁹⁺ for Base64 encoding and decoding, types⁸⁺ for built-in object type check, and Aspect¹¹⁺ for instrumentation and replacement on methods.

NOTE

The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import util from '@ohos.util';

util.format⁹⁺

format(format: string, ...args: Object[]): string

Formats a string by replacing the placeholders in it.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Format Specifiers

Example

import util from '@ohos.util';

interface utilAddresstype {
  city: string;
  country: string;
}
interface utilPersontype {
  name: string;
  age: number;
  address: utilAddresstype;
}

let name = 'John';
let age = 20;
let formattedString = util.format('My name is %s and I am %s years old', name, age);
console.info(formattedString);
// Output: My name is John and I am 20 years old
let num = 10.5;
formattedString = util.format('The number is %d', num);
console.info(formattedString);
// Output: The number is 10.5.
num = 100.5;
formattedString = util.format('The number is %i', num);
console.info(formattedString);
// Output: The number is 100.
const pi = 3.141592653;
formattedString = util.format('The value of pi is %f', pi);
console.info(formattedString);
// Output: The value of pi is 3.141592653
const obj: Record<string,number | string> = { "name": 'John', "age": 20 };
formattedString = util.format('The object is %j', obj);
console.info(formattedString);
// Output: The object is {"name":"John","age":20}.
const person: utilPersontype = {
  name: 'John',
  age: 20,
  address: {
    city: 'New York',
    country: 'USA'
  }
};
console.info(util.format('Formatted object using %%O: %O', person));
console.info(util.format('Formatted object using %%o: %o', person));
/*
Output:
Formatted object using %O: { name: 'John',
  age: 20,
  address:
  { city: 'New York',
    country: 'USA' } }
Formatted object using %o: { name: 'John',
  age: 20,
  address:
  { city: 'New York',
    country: 'USA' } }
*/
const percentage = 80;
let arg = 'homework';
formattedString = util.format('John finished %d%% of the %s', percentage, arg);
console.info(formattedString);
// Output: John finished 80% of the homework

util.errnoToString⁹⁺

errnoToString(errno: number): string

Obtains detailed information about a system error code.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let errnum = -1; // -1 is a system error code.
let result = util.errnoToString(errnum);
console.info("result = " + result);

Some error code and message examples

util.callbackWrapper

callbackWrapper(original: Function): (err: Object, value: Object )=>void

Calls back an asynchronous function. In the callback, the first parameter indicates the cause of the rejection (the value is null if the promise has been resolved), and the second parameter indicates the resolved value.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

async function fn() {
  return 'hello world';
}
let cb = util.callbackWrapper(fn);
cb(1, (err : Object, ret : string) => {
  if (err) throw new Error;
  console.info(ret);
});

util.promisify⁹⁺

promisify(original: (err: Object, value: Object) => void): Function

Processes an asynchronous function and returns a promise.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

async function fn() {
  return 'hello world';
}
const addCall = util.promisify(util.callbackWrapper(fn));
(async () => {
  try {
    let res: string = await addCall();
    console.info(res);
  } catch (err) {
    console.info(err);
  }
})();

util.generateRandomUUID⁹⁺

generateRandomUUID(entropyCache?: boolean): string

Uses a secure random number generator to generate a random universally unique identifier (UUID) of the string type in RFC 4122 version 4.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let uuid = util.generateRandomUUID(true);
console.info("RFC 4122 Version 4 UUID:" + uuid);
// Output a random UUID.

util.generateRandomBinaryUUID⁹⁺

generateRandomBinaryUUID(entropyCache?: boolean): Uint8Array

Uses a secure random number generator to generate a random UUID of the Uint8Array type in RFC 4122 version 4.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let uuid = util.generateRandomBinaryUUID(true);
console.info(JSON.stringify(uuid));
// Output:
// 138,188,43,243,62,254,70,119,130,20,235,222,199,164,140,150

util.parseUUID⁹⁺

parseUUID(uuid: string): Uint8Array

Converts a UUID of the string type generated by generateRandomUUID to a UUID of the Uint8Array type generated by generateRandomBinaryUUID, as described in RFC 4122 version 4.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let uuid = util.parseUUID("84bdf796-66cc-4655-9b89-d6218d100f9c");
console.info(JSON.stringify(uuid));
// Output:
// 132,189,247,150,102,204,70,85,155,137,214,33,141,16,15,156

util.printf^(deprecated)

printf(format: string, ...args: Object[]): string

Formats a string by replacing the placeholders in it.

NOTE

This API is supported since API version 7 and deprecated since API version 9. You are advised to use util.format⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let res = util.printf("%s", "hello world!");
console.info(res);

util.getErrorString^(deprecated)

getErrorString(errno: number): string

Obtains detailed information about a system error code.

NOTE

This API is supported since API version 7 and deprecated since API version 9. You are advised to use util.errnoToString⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let errnum = -1; // -1 is a system error code.
let result = util.getErrorString(errnum);
console.info("result = " + result);

util.promiseWrapper^(deprecated)

promiseWrapper(original: (err: Object, value: Object) => void): Object

Processes an asynchronous function and returns a promise.

NOTE

This API is unavailable. You are advised to use util.promisify⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

TextDecoderOptions¹¹⁺

System capability: SystemCapability.Utils.Lang

Decoding-related options, which include fatal and ignoreBOM.

DecodeWithStreamOptions¹¹⁺

System capability: SystemCapability.Utils.Lang

Defines whether decoding follows data blocks.

Aspect¹¹⁺

Provides APIs that support Aspect Oriented Programming (AOP). These APIs can be used to perform instrumentation or replacement on class methods.

addBefore¹¹⁺

static addBefore(targetClass: Object, methodName: string, isStatic: boolean, before: Function): void

Inserts a function before a method of a class object. The inserted function is executed in prior to the original method of the class object.

System capability: SystemCapability.Utils.Lang

Parameters

Example

class MyClass {
  msg: string = 'msg000';
  foo(arg: string): string {
    console.info('foo arg is ' + arg);
    return this.msg;
  }

  static data: string = 'data000';
  static bar(arg: string): string {
    console.info('bar arg is ' + arg);
	return MyClass.data;
  }
}

let asp = new MyClass();
let result = asp.foo('123');
// Output: foo arg is 123
console.info('result is ' + result);
// Output: result is msg000
console.info('asp.msg is ' + asp.msg);
// Output: asp.msg is msg000

util.Aspect.addBefore(MyClass, 'foo', false, (instance: MyClass, arg: string) => {
  console.info('arg is ' + arg);
  instance.msg = 'msg111';
  console.info('msg is changed to ' + instance.msg)
});

result = asp.foo('123');
// Output: arg is 123
// Output: msg is changed to msg111
// Output: foo arg is 123
console.info('result is ' + result);
// Output: result is msg111
console.info('asp.msg is ' + asp.msg);
// Output: asp.msg is msg111


let res = MyClass.bar('456');
// Output: bar arg is 456
console.info('res is ' + res);
// Output: res is data000
console.info('MyClass.data is ' + MyClass.data);
// Output: MyClass.data is data000

util.Aspect.addBefore(MyClass, 'bar', true, (target: Object, arg: string) => {
  console.info('arg is ' + arg);
  let newVal = 'data111';
  Reflect.set(target, 'data', newVal);
  console.info('data is changed to ' + newVal);
});

res = MyClass.bar('456');
// Output: arg is 456
// Output: data is changed to data111
// Output: bar arg is 456
console.info('res is ' + res);
//Output: res is data111
console.info('MyClass.data is ' + MyClass.data);
// Output: MyClass.data is data111

addAfter¹¹⁺

static addAfter(targetClass: Object, methodName: string, isStatic: boolean, after: Function): void

Inserts a function after a method of a class object. The final return value is the return value of the function inserted.

System capability: SystemCapability.Utils.Lang

Parameters

Example

class MyClass {
  msg: string = 'msg000';
  foo(arg: string): string {
    console.info('foo arg is ' + arg);
    return this.msg;
  }
}

let asp = new MyClass();
let result = asp.foo('123');
// Output: foo arg is 123
console.info('result is ' + result);
// Output: result is msg000
console.info('asp.msg is ' + asp.msg);
// Output: asp.msg is msg000

util.Aspect.addAfter(MyClass, 'foo', false, (instance: MyClass, ret: string, arg: string): string => {
  console.info('arg is ' + arg);
  console.info('ret is ' + ret);
  instance.msg = 'msg111';
  console.info('msg is changed to ' + instance.msg);
  return 'msg222';
});

result = asp.foo('123');
// Output: foo arg is 123
// Output: arg is 123
// Output: ret is msg000
// Output: msg is changed to msg111
console.info('result is ' + result);
// Output: result is msg222
console.info('asp.msg is ' + asp.msg);
// Output: asp.msg is msg111

// Examples of addBefore() and addAfter()
class AroundTest {
  foo(arg: string) {
    console.info('execute foo with arg ' + arg);
  }
}
util.Aspect.addBefore(AroundTest, 'foo', false, () => {
  console.info('execute before');
});
util.Aspect.addAfter(AroundTest, 'foo', false, () => {
  console.info('execute after');
});

(new AroundTest()).foo('hello');
// Output: execute before
// Output: execute foo with arg hello
// Output: execute after

replace¹¹⁺

static replace(targetClass: Object, methodName: string, isStatic: boolean, instead: Function) : void

Replaces a method of a class object with another function. After the replacement, only the new function logic is executed. The final return value is the return value of the new function.

System capability: SystemCapability.Utils.Lang

Parameters

Example

class MyClass {
  msg: string = 'msg000';
  foo(arg: string): string {
    console.info('foo arg is ' + arg);
    return this.msg;
  }
}

let asp = new MyClass();
let result = asp.foo('123');
// Output: foo arg is 123
console.info('result is ' + result);
// Output: result is msg000
console.info('asp.msg is ' + asp.msg);
// Output: asp.msg is msg000

util.Aspect.replace(MyClass, 'foo', false, (instance: MyClass, arg: string): string => {
  console.info('execute instead')
  console.info('arg is ' + arg);
  instance.msg = 'msg111';
  console.info('msg is changed to ' + instance.msg);
  return 'msg222';
});

result = asp.foo('123');
// Output: execute instead
// Output: arg is 123
// Output: msg is changed to msg111
console.info('result is ' + result);
// Output: result is msg222
console.info('asp.msg is ' + asp.msg);
// Output: asp.msg is msg111

TextDecoder

Provides APIs to decode byte arrays into strings. It supports multiple formats, including UTF-8, UTF-16LE, UTF-16BE, ISO-8859, and Windows-1251.

Attributes

System capability: SystemCapability.Utils.Lang

constructor⁹⁺

constructor()

A constructor used to create a TextDecoder object.

System capability: SystemCapability.Utils.Lang

Example

let result = new util.TextDecoder();
let retStr = result.encoding;

create⁹⁺

static create(encoding?: string, options?: TextDecoderOptions): TextDecoder

Creates a TextDecoder object. It provides the same function as the deprecated argument constructor.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let textDecoderOptions: util.TextDecoderOptions = {
  fatal: false,
  ignoreBOM : true
}
let result = util.TextDecoder.create('utf-8', textDecoderOptions)
let retStr = result.encoding

decodeWithStream⁹⁺

decodeWithStream(input: Uint8Array, options?: DecodeWithStreamOptions): string

Decodes the input content into a string.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let textDecoderOptions: util.TextDecoderOptions = {
  fatal: false,
  ignoreBOM : true
}
let decodeWithStreamOptions: util.DecodeWithStreamOptions = {
  stream: false
}
let textDecoder = util.TextDecoder.create('utf-8', textDecoderOptions);
let result = new Uint8Array(6);
result[0] = 0xEF;
result[1] = 0xBB;
result[2] = 0xBF;
result[3] = 0x61;
result[4] = 0x62;
result[5] = 0x63;
console.info("input num:");
let retStr = textDecoder.decodeWithStream(result , decodeWithStreamOptions);
console.info("retStr = " + retStr);

constructor^(deprecated)

constructor(encoding?: string, options?: { fatal?: boolean; ignoreBOM?: boolean })

A constructor used to create a TextDecoder object.

NOTE

This API is supported since API version 7 and deprecated since API version 9. You are advised to use create⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Table 1 options

Example

let textDecoder = new util.TextDecoder("utf-8",{ignoreBOM: true});

decode^(deprecated)

decode(input: Uint8Array, options?: { stream?: false }): string

Decodes the input content into a string.

NOTE

This API is supported since API version 7 and deprecated since API version 9. You are advised to use decodeWithStream⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Table 2 options

Return value

Example

let textDecoder = new util.TextDecoder("utf-8",{ignoreBOM: true});
let result = new Uint8Array(6);
result[0] = 0xEF;
result[1] = 0xBB;
result[2] = 0xBF;
result[3] = 0x61;
result[4] = 0x62;
result[5] = 0x63;
console.info("input num:");
let retStr = textDecoder.decode( result , {stream: false});
console.info("retStr = " + retStr);

EncodeIntoUint8ArrayInfo¹¹⁺

System capability: SystemCapability.Utils.Lang

Defines encoded text.

TextEncoder

Provides APIs to encode strings into byte arrays. It supports multiple formats, including UTF-8, UTF-16LE, and UTF-16BE. When TextEncoder is used for encoding, the number of bytes occupied by a character varies according to the encoding format. For example, a Chinese character usually occupies three bytes in UTF-8 encoding format but two bytes in UTF-16LE or UTF-16BE encoding format. Therefore, when using TextEncoder, you must explicitly specify the encoding format to obtain the required encoding result.

Attributes

System capability: SystemCapability.Utils.Lang

constructor

constructor()

A constructor used to create a TextEncoder object.

System capability: SystemCapability.Utils.Lang

Example

let textEncoder = new util.TextEncoder();

constructor⁹⁺

constructor(encoding?: string)

A constructor used to create a TextEncoder object.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let textEncoder = new util.TextEncoder("utf-8");

encodeInto⁹⁺

encodeInto(input?: string): Uint8Array

Encodes the input content into a Uint8Array object.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let textEncoder = new util.TextEncoder();
let buffer = new ArrayBuffer(20);
let result = new Uint8Array(buffer);
result = textEncoder.encodeInto("\uD800¥¥");

encodeIntoUint8Array⁹⁺

encodeIntoUint8Array(input: string, dest: Uint8Array): EncodeIntoUint8ArrayInfo

Encodes the input content into a Uint8Array object.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.TextEncoder();
let buffer = new ArrayBuffer(4);
let dest = new Uint8Array(buffer);
let result = new Object();
result = that.encodeIntoUint8Array('abcd', dest);

encodeInto^(deprecated)

encodeInto(input: string, dest: Uint8Array): { read: number; written: number }

Stores the UTF-8 encoded text.

NOTE

This API is supported since API version 7 and deprecated since API version 9. You are advised to use encodeIntoUint8Array⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.TextEncoder();
let buffer = new ArrayBuffer(4);
let dest = new Uint8Array(buffer);
let result = new Object();
result = that.encodeInto('abcd', dest);

encode^(deprecated)

encode(input?: string): Uint8Array

Encodes the input content in to a Uint8Array object.

NOTE

This API is supported since API version 7 and deprecated since API version 9. You are advised to use encodeInto⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let textEncoder = new util.TextEncoder();
let buffer = new ArrayBuffer(20);
let result = new Uint8Array(buffer);
result = textEncoder.encode("\uD800¥¥");

RationalNumber⁸⁺

Provides APIs to compare rational numbers and obtain numerators and denominators. For example, the toString() API can be used to convert a rational number into a string.

constructor⁹⁺

constructor()

A constructor used to create a RationalNumber object.

System capability: SystemCapability.Utils.Lang

Example

let rationalNumber = new util.RationalNumber();

parseRationalNumber⁹⁺

parseRationalNumber(numerator: number,denominator: number): RationalNumber

Create a RationalNumber instance with a given numerator and denominator.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let rationalNumber = util.RationalNumber.parseRationalNumber(1,2);

createRationalFromString⁸⁺

static createRationalFromString​(rationalString: string): RationalNumber​

Creates a RationalNumber object based on the given string.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let rational = util.RationalNumber.createRationalFromString("3/4");

compare⁹⁺

compare​(another: RationalNumber): number​

Compares this RationalNumber object with another RationalNumber object.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let rationalNumber = util.RationalNumber.parseRationalNumber(1,2);
let rational = util.RationalNumber.createRationalFromString("3/4");
let result = rationalNumber.compare(rational);
console.info("result = " + result);
// Output: result = -1

valueOf⁸⁺

valueOf(): number

Obtains the value of this RationalNumber object as an integer or a floating-point number.

System capability: SystemCapability.Utils.Lang

Return value

Example

let rationalNumber = new util.RationalNumber(1,2);
let result = rationalNumber.valueOf();
console.info("result = " + result);
// Output: result = 0.5

You are advised to use the following code snippet for API version 9 and later versions:

let rationalNumber = util.RationalNumber.parseRationalNumber(1,2);
let result = rationalNumber.valueOf();
console.info("result = " + result);
// Output: result = 0.5

equals⁸⁺

equals​(obj: Object): boolean

Checks whether this RationalNumber object equals the given object.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let rationalNumber = new util.RationalNumber(1,2);
let rational = util.RationalNumber.createRationalFromString("3/4");
let result = rationalNumber.equals(rational);
console.info("result = " + result);
// Output: result = false

You are advised to use the following code snippet for API version 9 and later versions:

let rationalNumber = util.RationalNumber.parseRationalNumber(1,2);
let rational = util.RationalNumber.createRationalFromString("3/4");
let result = rationalNumber.equals(rational);
console.info("result = " + result);
// Output: result = false

getCommonFactor⁹⁺

getCommonFactor(number1: number,number2: number): number

Obtains the greatest common divisor of two specified integers.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let result = util.RationalNumber.getCommonFactor(4,6);
console.info("result = " + result);
// Output: result = 2

getNumerator⁸⁺

getNumerator​(): number

Obtains the numerator of this RationalNumber object.

System capability: SystemCapability.Utils.Lang

Return value

Example

let rationalNumber = new util.RationalNumber(1,2);
let result = rationalNumber.getNumerator();
console.info("result = " + result);
// Output: result = 1

You are advised to use the following code snippet for API version 9 and later versions:

let rationalNumber = util.RationalNumber.parseRationalNumber(1,2);
let result = rationalNumber.getNumerator();
console.info("result = " + result);
// Output: result = 1

getDenominator⁸⁺

getDenominator​(): number

Obtains the denominator of this RationalNumber object.

System capability: SystemCapability.Utils.Lang

Return value

Example

let rationalNumber = new util.RationalNumber(1,2);
let result = rationalNumber.getDenominator();
console.info("result = " + result);
// Output: result = 2

You are advised to use the following code snippet for API version 9 and later versions:

let rationalNumber = util.RationalNumber.parseRationalNumber(1,2)
let result = rationalNumber.getDenominator();
console.info("result = " + result);
// Output: result = 2

isZero⁸⁺

isZero​():boolean

Checks whether this RationalNumber object is 0.

System capability: SystemCapability.Utils.Lang

Return value

Example

let rationalNumber = new util.RationalNumber(1,2);
let result = rationalNumber.isZero();
console.info("result = " + result);
// Output: result = false

You are advised to use the following code snippet for API version 9 and later versions:

let rationalNumber = util.RationalNumber.parseRationalNumber(1,2);
let result = rationalNumber.isZero();
console.info("result = " + result);
// Output: result = false

isNaN⁸⁺

isNaN​(): boolean

Checks whether this RationalNumber object is a Not a Number (NaN).

System capability: SystemCapability.Utils.Lang

Return value

Example

let rationalNumber = new util.RationalNumber(1,2);
let result = rationalNumber.isNaN();
console.info("result = " + result);
// Output: result = false

You are advised to use the following code snippet for API version 9 and later versions:

let rationalNumber = util.RationalNumber.parseRationalNumber(1,2);
let result = rationalNumber.isNaN();
console.info("result = " + result);
// Output: result = false

isFinite⁸⁺

isFinite​():boolean

Checks whether this RationalNumber object represents a finite value.

System capability: SystemCapability.Utils.Lang

Return value

Example

let rationalNumber = new util.RationalNumber(1,2);
let result = rationalNumber.isFinite();
console.info("result = " + result);
// Output: result = true

You are advised to use the following code snippet for API version 9 and later versions:

let rationalNumber = util.RationalNumber.parseRationalNumber(1,2);
let result = rationalNumber.isFinite();
console.info("result = " + result);
// Output: result = true

toString⁸⁺

toString​(): string

Obtains the string representation of this RationalNumber object.

System capability: SystemCapability.Utils.Lang

Return value

Example

let rationalNumber = new util.RationalNumber(1,2);
let result = rationalNumber.toString();
console.info("result = " + result);
// Output: result = 1/2

You are advised to use the following code snippet for API version 9 and later versions:

let rationalNumber = util.RationalNumber.parseRationalNumber(1,2);
let result = rationalNumber.toString();
console.info("result = " + result);
// Output: result = 1/2

constructor^(deprecated)

constructor(numerator: number,denominator: number)

A constructor used to create a RationalNumber object.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use parserationalnumber⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let rationalNumber = new util.RationalNumber(1,2);

compareTo^(deprecated)

compareTo​(another: RationalNumber): number​

Compares this RationalNumber object with a given object.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use compare⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let rationalNumber = new util.RationalNumber(1,2);
let rational = util.RationalNumber.createRationalFromString("3/4");
let result = rationalNumber.compareTo(rational);

getCommonDivisor^(deprecated)

static getCommonDivisor​(number1: number,number2: number): number

Obtains the greatest common divisor of two specified integers.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use getCommonFactor⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let rationalNumber = new util.RationalNumber(1,2);
let result = util.RationalNumber.getCommonDivisor(4,6);

LRUCache⁹⁺

Provides APIs to discard the least recently used data to make rooms for new elements when the cache is full. This class uses the Least Recently Used (LRU) algorithm, which believes that the recently used data may be accessed again in the near future and the least accessed data is the least valuable data and should be removed from the cache.

Attributes

System capability: SystemCapability.Utils.Lang

Example

let  pro : util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
pro.put(1,8);
let result = pro.length;

constructor⁹⁺

constructor(capacity?: number)

A constructor used to create a LRUCache instance. The default capacity of the cache is 64.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let lrubuffer : util.LRUCache<number, number> = new util.LRUCache();

updateCapacity⁹⁺

updateCapacity(newCapacity: number): void

Changes the cache capacity. If the new capacity is less than or equal to 0, an exception will be thrown.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.updateCapacity(100);

toString⁹⁺

toString(): string

Obtains the string representation of this cache.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
pro.get(2);
pro.get(3);
console.info(pro.toString());
// Output: LRUCache[ maxSize = 64, hits = 1, misses = 1, hitRate = 50% ]
// maxSize: maximum size of the cache. hits: number of matched queries. misses: number of mismatched queries. hitRate: matching rate.

getCapacity⁹⁺

getCapacity(): number

Obtains the capacity of this cache.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
let result = pro.getCapacity();

clear⁹⁺

clear(): void

Clears key-value pairs from this cache. The afterRemoval() method will be called to perform subsequent operations.

System capability: SystemCapability.Utils.Lang

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
let result = pro.length;
pro.clear();

getCreateCount⁹⁺

getCreateCount(): number

Obtains the number of times that an object is created.

System capability: SystemCapability.Utils.Lang

Return value

Example

// Create the ChildLRUCache class that inherits LRUCache, and override createDefault() to return a non-undefined value.
class ChildLRUCache extends util.LRUCache<number, number> {
  constructor() {
    super();
  }

  createDefault(key: number): number {
    return key;
  }
}
let lru = new ChildLRUCache();
lru.put(2,10);
lru.get(3);
lru.get(5);
let res = lru.getCreateCount();

getMissCount⁹⁺

getMissCount(): number

Obtains the number of times that the queried values are mismatched.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
pro.get(2);
let result = pro.getMissCount();

getRemovalCount⁹⁺

getRemovalCount(): number

Obtains the number of times that key-value pairs in the cache are recycled.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
pro.updateCapacity(2);
pro.put(50,22);
let result = pro.getRemovalCount();

getMatchCount⁹⁺

getMatchCount(): number

Obtains the number of times that the queried values are matched.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
pro.get(2);
let result = pro.getMatchCount();

getPutCount⁹⁺

getPutCount(): number

Obtains the number of additions to this cache.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
let result = pro.getPutCount();

isEmpty⁹⁺

isEmpty(): boolean

Checks whether this cache is empty.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
let result = pro.isEmpty();

get⁹⁺

get(key: K): V | undefined

Obtains the value of the specified key.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
let result  = pro.get(2);

put⁹⁺

put(key: K,value: V): V

Adds a key-value pair to this cache.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
let result = pro.put(2,10);

values⁹⁺

values(): V[]

Obtains all values in this cache, listed from the most to the least recently accessed.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number|string,number|string> = new util.LRUCache();
pro.put(2,10);
pro.put(2,"anhu");
pro.put("afaf","grfb");
let result = pro.values();

keys⁹⁺

keys(): K[]

Obtains all keys in this cache, listed from the most to the least recently accessed.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
let result = pro.keys();

remove⁹⁺

remove(key: K): V | undefined

Removes the specified key and its value from this cache.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
let result = pro.remove(20);

afterRemoval⁹⁺

afterRemoval(isEvict: boolean,key: K,value: V,newValue: V): void

Performs subsequent operations after a value is removed.

System capability: SystemCapability.Utils.Lang

Parameters

Example

class ChildLRUCache<K, V> extends util.LRUCache<K, V> {
  constructor(capacity?: number) {
    super(capacity);
  }

  afterRemoval(isEvict: boolean, key: K, value: V, newValue: V): void {
    if (isEvict === true) {
      console.info('key: ' + key);
      console.info('value: ' + value);
      console.info('newValue: ' + newValue);
    }
  }
}
let lru: ChildLRUCache<number, number>= new ChildLRUCache(2);
lru.put(1, 1);
lru.put(2, 2);
lru.put(3, 3);

contains⁹⁺

contains(key: K): boolean

Checks whether this cache contains the specified key.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let pro : util.LRUCache<number | object, number> = new util.LRUCache();
pro.put(2,10);
class Lru{
s : string = "";
}
let obj : Lru = {s : "key" };
let result = pro.contains(obj);

createDefault⁹⁺

createDefault(key: K): V

Creates a value if the value of the specified key is not available.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
let result = pro.createDefault(50);

entries⁹⁺

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

Obtains a new iterator object that contains all key-value pairs in this object.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
pro.put(3,15);
let pair:Iterable<Object[]> = pro.entries();
let arrayValue = Array.from(pair);
for (let value of arrayValue) {
  console.info(value[0]+ ', '+ value[1]);
}

[Symbol.iterator]⁹⁺

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

Obtains a two-dimensional array in key-value pairs.

NOTE

This API cannot be used in .ets files.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro: util.LRUCache<number, number> = new util.LRUCache();
pro.put(2,10);
pro.put(3,15);
let pair:Iterable<Object[]> = pro[Symbol.iterator]();
let arrayValue = Array.from(pair);
for (let value of arrayValue) {
  console.info(value[0]+ ', '+ value[1]);
}

ScopeComparable⁸⁺

The values of the ScopeComparable type are used to implement the compareTo method. Therefore, ensure that the input parameters are comparable.

System capability: SystemCapability.Utils.Lang

compareTo⁸⁺

compareTo(other: ScopeComparable): boolean

Compares two values and returns a Boolean value.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

Create a class to implement the compareTo method. The Temperature class is used as an example in the following sample code.

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

ScopeType⁸⁺

Defines the type of values in a Scope object.

System capability: SystemCapability.Utils.Lang

ScopeHelper⁹⁺

Provides APIs to define the valid range of a field. The constructor of this class creates comparable objects with lower and upper limits.

constructor⁹⁺

constructor(lowerObj: ScopeType, upperObj: ScopeType)

A constructor used to create a ScopeHelper object with the specified upper and lower limits.

System capability: SystemCapability.Utils.Lang

Parameters

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}
let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let range = new util.ScopeHelper(tempLower, tempUpper);

toString⁹⁺

toString(): string

Obtains a string representation that contains this Scope.

System capability: SystemCapability.Utils.Lang

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let range = new util.ScopeHelper(tempLower, tempUpper);
let result = range.toString();

intersect⁹⁺

intersect(range: ScopeHelper): ScopeHelper

Obtains the intersection of this Scope and the given Scope.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let range = new util.ScopeHelper(tempLower, tempUpper);
let tempMiDF = new Temperature(35);
let tempMidS = new Temperature(39);
let rangeFir = new util.ScopeHelper(tempMiDF, tempMidS);
range.intersect(rangeFir);

intersect⁹⁺

intersect(lowerObj:ScopeType,upperObj:ScopeType):ScopeHelper

Obtains the intersection of this Scope and the given lower and upper limits.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let tempMiDF = new Temperature(35);
let tempMidS = new Temperature(39);
let range = new util.ScopeHelper(tempLower, tempUpper);
let result = range.intersect(tempMiDF, tempMidS);

getUpper⁹⁺

getUpper(): ScopeType

Obtains the upper limit of this Scope.

System capability: SystemCapability.Utils.Lang

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let range = new util.ScopeHelper(tempLower, tempUpper);
let result = range.getUpper();

getLower⁹⁺

getLower(): ScopeType

Obtains the lower limit of this Scope.

System capability: SystemCapability.Utils.Lang

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let range = new util.ScopeHelper(tempLower, tempUpper);
let result = range.getLower();

expand⁹⁺

expand(lowerObj: ScopeType,upperObj: ScopeType): ScopeHelper

Obtains the union set of this Scope and the given lower and upper limits.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let tempMiDF = new Temperature(35);
let tempMidS = new Temperature(39);
let range = new util.ScopeHelper(tempLower, tempUpper);
let result = range.expand(tempMiDF, tempMidS);

expand⁹⁺

expand(range: ScopeHelper): ScopeHelper

Obtains the union set of this Scope and the given Scope.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let tempMiDF = new Temperature(35);
let tempMidS = new Temperature(39);
let range = new util.ScopeHelper(tempLower, tempUpper);
let rangeFir = new util.ScopeHelper(tempMiDF, tempMidS);
let result = range.expand(rangeFir);

expand⁹⁺

expand(value: ScopeType): ScopeHelper

Obtains the union set of this Scope and the given value.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let tempMiDF = new Temperature(35);
let range = new util.ScopeHelper(tempLower, tempUpper);
let result = range.expand(tempMiDF);

contains⁹⁺

contains(value: ScopeType): boolean

Checks whether a value is within this Scope.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let tempMiDF = new Temperature(35);
let range = new util.ScopeHelper(tempLower, tempUpper);
let result = range.contains(tempMiDF);

contains⁹⁺

contains(range: ScopeHelper): boolean

Checks whether a range is within this Scope.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let range = new util.ScopeHelper(tempLower, tempUpper);
let tempLess = new Temperature(20);
let tempMore = new Temperature(45);
let rangeSec = new util.ScopeHelper(tempLess, tempMore);
let result = range.contains(rangeSec);

clamp⁹⁺

clamp(value: ScopeType): ScopeType

Limits a value to this Scope.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

class Temperature{
  private readonly _temp: number;
  constructor(value : number) {
    this._temp = value;
  }
  compareTo(value : Temperature ) {
    return this._temp >= value.getTemp();
  }
  getTemp() {
    return this._temp;
  }
  toString() : string {
    return this._temp.toString();
  }
}

let tempLower = new Temperature(30);
let tempUpper = new Temperature(40);
let tempMiDF = new Temperature(35);
let range = new util.ScopeHelper(tempLower, tempUpper);
let result = range.clamp(tempMiDF);

Base64Helper⁹⁺

Provides encoding and decoding for Base64 and Base64URL. The Base64 encoding table contains 64 characters, which are the uppercase letters (A-Z), lowercase letters (a-z), digits (0-9), and the special characters plus sign (+) and slash (/). During encoding, the original data is divided into groups of three bytes, and each group contains a 6-bit number. Then, the corresponding characters in the Base64 encoding table are used to represent these numbers. If the last group contains only one or two bytes, the equal sign (=) is used for padding.

constructor⁹⁺

constructor()

A constructor used to create a Base64Helper instance.

System capability: SystemCapability.Utils.Lang

Example

let base64 = new  util.Base64Helper();

encodeSync⁹⁺

encodeSync(src: Uint8Array): Uint8Array

Encodes the input content into a Uint8Array object.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.Base64Helper();
let array = new Uint8Array([115,49,51]);
let result = that.encodeSync(array);

encodeToStringSync⁹⁺

encodeToStringSync(src: Uint8Array, options?: Type): string

Encodes the input content into a string. This API returns the result synchronously.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.Base64Helper();
let array = new Uint8Array([77,97,110,105,115,100,105,115,116,105,110,103,117,105,115,104,101,100,110,111,116,111,110,108,121,98,121,104,105,115,114,101,97,115,111,110,98,117,116,98,121,116,104,105,115,115,105,110,103,117,108,97,114,112,97,115,115,105,111,110,102,114,111,109,111,116,104,101,114,97,110,105,109,97,108,115,119,104,105,99,104,105,115,97,108,117,115,116,111,102,116,104,101,109,105,110,100,101,120,99,101,101,100,115,116,104,101,115,104,111,114,116,118,101,104,101,109,101,110,99,101,111,102,97,110,121,99,97,114,110,97,108,112,108,101,97,115,117,114,101]);
let result = that.encodeToStringSync(array, util.Type.MIME);

decodeSync⁹⁺

decodeSync(src: Uint8Array | string, options?: Type): Uint8Array

Decodes a string into a Uint8Array object. This API returns the result synchronously.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.Base64Helper();
let buff = 'TWFuaXNkaXN0aW5ndWlzaGVkbm90b25seWJ5aGlzcmVhc29uYnV0Ynl0aGlzc2luZ3VsYXJwYXNz\r\naW9uZnJvbW90aGVyYW5pbWFsc3doaWNoaXNhbHVzdG9mdGhlbWluZGV4Y2VlZHN0aGVzaG9ydHZl\r\naGVtZW5jZW9mYW55Y2FybmFscGxlYXN1cmU=\r\n';
let result = that.decodeSync(buff, util.Type.MIME);

encode⁹⁺

encode(src: Uint8Array): Promise<Uint8Array>

Encodes the input content into a Uint8Array object. This API uses a promise to return the result.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.Base64Helper();
let array = new Uint8Array([115,49,51]);
let rarray = new Uint8Array([99,122,69,122]);
that.encode(array).then(val=>{
  for (let i = 0; i < rarray.length; i++) {
    console.info(val[i].toString());
  }
})

encodeToString⁹⁺

encodeToString(src: Uint8Array, options?: Type): Promise<string>

Encodes the input content into a string. This API uses a promise to return the result.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.Base64Helper();
let array = new Uint8Array([77,97,110,105,115,100,105,115,116,105,110,103,117,105,115,104,101,100,110,111,116,111,110,108,121,98,121,104,105,115,114,101,97,115,111,110,98,117,116,98,121,116,104,105,115,115,105,110,103,117,108,97,114,112,97,115,115,105,111,110,102,114,111,109,111,116,104,101,114,97,110,105,109,97,108,115,119,104,105,99,104,105,115,97,108,117,115,116,111,102,116,104,101,109,105,110,100,101,120,99,101,101,100,115,116,104,101,115,104,111,114,116,118,101,104,101,109,101,110,99,101,111,102,97,110,121,99,97,114,110,97,108,112,108,101,97,115,117,114,101]);
that.encodeToString(array, util.Type.MIME).then(val=>{
  // Add information as required.
})

decode⁹⁺

decode(src: Uint8Array | string, options?: Type): Promise<Uint8Array>

Decodes the input content into a Uint8Array object. This API uses a promise to return the result.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.Base64Helper();
let array = 'TWFuaXNkaXN0aW5ndWlzaGVkbm90b25seWJ5aGlzcmVhc29uYnV0Ynl0aGlzc2luZ3VsYXJwYXNz\r\naW9uZnJvbW90aGVyYW5pbWFsc3doaWNoaXNhbHVzdG9mdGhlbWluZGV4Y2VlZHN0aGVzaG9ydHZl\r\naGVtZW5jZW9mYW55Y2FybmFscGxlYXN1cmU=\r\n';
that.decode(array, util.Type.MIME).then(val=>{
  // Add information as required.
})

Type¹⁰⁺

Enumerates the Base64 encoding formats.

System capability: SystemCapability.Utils.Lang

types⁸⁺

Provides APIs to check different types of built-in objects, such as ArrayBuffer, Map, and Set, so as to avoid exceptions or crashes caused by type errors.

constructor⁸⁺

constructor()

A constructor used to create a Types object.

System capability: SystemCapability.Utils.Lang

Example

let type = new util.types();

isAnyArrayBuffer⁸⁺

isAnyArrayBuffer(value: Object): boolean

Checks whether the input value is of the ArrayBuffer type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isAnyArrayBuffer(new ArrayBuffer(0));

isArrayBufferView⁸⁺

isArrayBufferView(value: Object): boolean

Checks whether the input value is of the ArrayBufferView type.

ArrayBufferView is a helper type representing any of the following: Int8Array, Int16Array, Int32Array, Uint8Array, Uint8ClampedArray, Uint32Array, Float32Array, Float64Array, and DataView.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isArrayBufferView(new Int8Array([]));

isArgumentsObject⁸⁺

isArgumentsObject(value: Object): boolean

Checks whether the input value is of the arguments type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
function foo() {
    let result = that.isArgumentsObject(arguments);
}
let f = foo();

isArrayBuffer⁸⁺

isArrayBuffer(value: Object): boolean

Checks whether the input value is of the ArrayBuffer type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isArrayBuffer(new ArrayBuffer(0));

isAsyncFunction⁸⁺

isAsyncFunction(value: Object): boolean

Checks whether the input value is an asynchronous function.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isAsyncFunction(async () => {});

isBooleanObject⁸⁺

isBooleanObject(value: Object): boolean

Checks whether the input value is of the Boolean type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isBooleanObject(new Boolean(true));

isBoxedPrimitive⁸⁺

isBoxedPrimitive(value: Object): boolean

Checks whether the input value is of the Boolean, Number, String, or Symbol type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isBoxedPrimitive(new Boolean(false));

isDataView⁸⁺

isDataView(value: Object): boolean

Checks whether the input value is of the DataView type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
const ab = new ArrayBuffer(20);
let result = that.isDataView(new DataView(ab));

isDate⁸⁺

isDate(value: Object): boolean

Checks whether the input value is of the Date type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isDate(new Date());

isExternal⁸⁺

isExternal(value: Object): boolean

Checks whether the input value is of the native external type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isExternal(true);

isFloat32Array⁸⁺

isFloat32Array(value: Object): boolean

Checks whether the input value is of the Float32Array type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isFloat32Array(new Float32Array());

isFloat64Array⁸⁺

isFloat64Array(value: Object): boolean

Checks whether the input value is of the Float64Array type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isFloat64Array(new Float64Array());

isGeneratorFunction⁸⁺

isGeneratorFunction(value: Object): boolean

Checks whether the input value is a generator function.

NOTE

This API cannot be used in .ets files.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isGeneratorFunction(function* foo() {});

isGeneratorObject⁸⁺

isGeneratorObject(value: Object): boolean

Checks whether the input value is a generator object.

NOTE

This API cannot be used in .ets files.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

// This API cannot be used in .ets files.
let that = new util.types();
function* foo() {};
const generator = foo();
let result = that.isGeneratorObject(generator);

isInt8Array⁸⁺

isInt8Array(value: Object): boolean

Checks whether the input value is of the Int8Array type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isInt8Array(new Int8Array([]));

isInt16Array⁸⁺

isInt16Array(value: Object): boolean

Checks whether the input value is of the Int16Array type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isInt16Array(new Int16Array([]));

isInt32Array⁸⁺

isInt32Array(value: Object): boolean

Checks whether the input value is of the Int32Array type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isInt32Array(new Int32Array([]));

isMap⁸⁺

isMap(value: Object): boolean

Checks whether the input value is of the Map type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isMap(new Map());

isMapIterator⁸⁺

isMapIterator(value: Object): boolean

Checks whether the input value is of the MapIterator type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
const map : Map<number,number> = new Map();
let result = that.isMapIterator(map.keys());

isNativeError⁸⁺

isNativeError(value: Object): boolean

Checks whether the input value is of the Error type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isNativeError(new TypeError());

isNumberObject⁸⁺

isNumberObject(value: Object): boolean

Checks whether the input value is a number object.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isNumberObject(new Number(0));

isPromise⁸⁺

isPromise(value: Object): boolean

Checks whether the input value is a promise.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isPromise(Promise.resolve(1));

isProxy⁸⁺

isProxy(value: Object): boolean

Checks whether the input value is a proxy.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

class Target{
}
let that = new util.types();
const target : Target = {};
const proxy = new Proxy(target, target);
let result = that.isProxy(proxy);

isRegExp⁸⁺

isRegExp(value: Object): boolean

Checks whether the input value is of the RegExp type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isRegExp(new RegExp('abc'));

isSet⁸⁺

isSet(value: Object): boolean

Checks whether the input value is of the Set type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let set : Set<number> = new Set();
let result = that.isSet(set);

isSetIterator⁸⁺

isSetIterator(value: Object): boolean

Checks whether the input value is of the SetIterator type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
const set : Set<number> = new Set();
let result = that.isSetIterator(set.keys());

isStringObject⁸⁺

isStringObject(value: Object): boolean

Checks whether the input value is a string object.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isStringObject(new String('foo'));

isSymbolObjec⁸⁺

isSymbolObject(value: Object): boolean

Checks whether the input value is a symbol object.

NOTE

This API cannot be used in .ets files.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

// This API cannot be used in .ets files.
let that = new util.types();
const symbols = Symbol('foo');
let result = that.isSymbolObject(Object(symbols));

isTypedArray⁸⁺

isTypedArray(value: Object): boolean

Checks whether the input value is of the TypedArray type.

TypedArray is a helper type representing any of the following: Int8Array, Int16Array, Int32Array, Uint8Array, Uint8ClampedArray, Uint16Array, Uint32Array, Float32Array, Float64Array, and DataView.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isTypedArray(new Float64Array([]));

isUint8Array⁸⁺

isUint8Array(value: Object): boolean

Checks whether the input value is of the Uint8Array type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isUint8Array(new Uint8Array([]));

isUint8ClampedArray⁸⁺

isUint8ClampedArray(value: Object): boolean

Checks whether the input value is of the Uint8ClampedArray type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isUint8ClampedArray(new Uint8ClampedArray([]));

isUint16Array⁸⁺

isUint16Array(value: Object): boolean

Checks whether the input value is of the Uint16Array type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isUint16Array(new Uint16Array([]));

isUint32Array⁸⁺

isUint32Array(value: Object): boolean

Checks whether the input value is of the Uint32Array type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isUint32Array(new Uint32Array([]));

isWeakMap⁸⁺

isWeakMap(value: Object): boolean

Checks whether the input value is of the WeakMap type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let value : WeakMap<object, number> = new WeakMap();
let result = that.isWeakMap(value);

isWeakSet⁸⁺

isWeakSet(value: Object): boolean

Checks whether the input value is of the WeakSet type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isWeakSet(new WeakSet());

isBigInt64Array⁸⁺

isBigInt64Array(value: Object): boolean

Checks whether the input value is of the BigInt64Array type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isBigInt64Array(new BigInt64Array([]));

isBigUint64Array⁸⁺

isBigUint64Array(value: Object): boolean

Checks whether the input value is of the BigUint64Array type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isBigUint64Array(new BigUint64Array([]));

isModuleNamespaceObject⁸⁺

isModuleNamespaceObject(value: Object): boolean

Checks whether the input value is a module namespace object.

NOTE

This API cannot be used in .ets files.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

// This API cannot be used in .ets files.
import url from '@ohos.url'
let that = new util.types();
let result = that.isModuleNamespaceObject(url);

isSharedArrayBuffer⁸⁺

isSharedArrayBuffer(value: Object): boolean

Checks whether the input value is of the SharedArrayBuffer type.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let that = new util.types();
let result = that.isSharedArrayBuffer(new SharedArrayBuffer(0));

LruBuffer^(deprecated)

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache⁹⁺ instead.

Attributes

System capability: SystemCapability.Utils.Lang

Example

let pro : util.LruBuffer<number,number>= new util.LruBuffer();
pro.put(2,10);
pro.put(1,8);
let result = pro.length;

constructor^(deprecated)

constructor(capacity?: number)

A constructor used to create a LruBuffer instance. The default capacity of the cache is 64.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.constructor⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let lrubuffer : util.LruBuffer<number,number> = new util.LruBuffer();

updateCapacity^(deprecated)

updateCapacity(newCapacity: number): void

Changes the cache capacity. If the new capacity is less than or equal to 0, an exception will be thrown.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.updateCapacity⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.updateCapacity(100);

toString^(deprecated)

toString(): string

Obtains the string representation of this cache.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.toString⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(2,10);
pro.get(2);
pro.remove(20);
let result = pro.toString();

getCapacity^(deprecated)

getCapacity(): number

Obtains the capacity of this cache.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.getCapacity⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
let result = pro.getCapacity();

clear^(deprecated)

clear(): void

Clears key-value pairs from this cache. The afterRemoval() method will be called to perform subsequent operations.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.clear⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(2,10);
let result = pro.length;
pro.clear();

getCreateCount^(deprecated)

getCreateCount(): number

Obtains the number of return values for createDefault().

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.getCreateCount⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(1,8);
let result = pro.getCreateCount();

getMissCount^(deprecated)

getMissCount(): number

Obtains the number of times that the queried values are mismatched.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.getMissCount⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(2,10);
pro.get(2);
let result = pro.getMissCount();

getRemovalCount^(deprecated)

getRemovalCount(): number

Obtains the number of removals from this cache.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.getRemovalCount⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(2,10);
pro.updateCapacity(2);
pro.put(50,22);
let result = pro.getRemovalCount();

getMatchCount^(deprecated)

getMatchCount(): number

Obtains the number of times that the queried values are matched.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.getMatchCount⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(2,10);
pro.get(2);
let result = pro.getMatchCount();

getPutCount^(deprecated)

getPutCount(): number

Obtains the number of additions to this cache.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.getPutCount⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(2,10);
let result = pro.getPutCount();

isEmpty^(deprecated)

isEmpty(): boolean

Checks whether this cache is empty.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.isEmpty⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(2,10);
let result = pro.isEmpty();

get^(deprecated)

get(key: K): V | undefined

Obtains the value of the specified key.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.get⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(2,10);
let result  = pro.get(2);

put^(deprecated)

put(key: K,value: V): V

Adds a key-value pair to this cache.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.put⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
let result = pro.put(2,10);

values^(deprecated)

values(): V[]

Obtains all values in this cache, listed from the most to the least recently accessed.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.values⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro : util.LruBuffer<number|string,number|string> = new util.LruBuffer();
pro.put(2,10);
pro.put(2,"anhu");
pro.put("afaf","grfb");
let result = pro.values();

keys^(deprecated)

keys(): K[]

Obtains all keys in this cache, listed from the most to the least recently accessed.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.keys⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(2,10);
let result = pro.keys();

remove^(deprecated)

remove(key: K): V | undefined

Removes the specified key and its value from this cache.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.remove⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Return value

Example

let pro : util.LruBuffer<number,number> = new util.LruBuffer();
pro.put(2,10);
let result = pro.remove(20);

afterRemoval^(deprecated)

afterRemoval(isEvict: boolean,key: K,value: V,newValue: V): void

Performs subsequent operations after a value is removed.

NOTE

This API is supported since API version 8 and deprecated since API version 9. You are advised to use LRUCache.afterRemoval⁹⁺ instead.

System capability: SystemCapability.Utils.Lang

Parameters

Example

class ChildLruBuffer<K, V> extends util.LruBuffer<K, V> {
  constructor(capacity?: number) {
    super(capacity);
  }

  afterRemoval(isEvict: boolean, key: K, value: V, newValue: V): void {
    if (isEvict === true) {
      console.info('key: ' + key);
      console.info('value: ' + value);
      console.info('newValue: ' + newValue);
    }
  }
}
let lru: ChildLruBuffer<number, number> = new ChildLruBuffer(2);
lru.put(11, 1);
lru.put(22, 2);
lru.put(33, 3);

contains^(deprecated)

contains(key: K): boolean

Checks whether this cache contains the specified key.