harmony 鸿蒙@ohos.util.PlainArray (Nonlinear Container PlainArray)
@ohos.util.PlainArray (Nonlinear Container PlainArray)
PlainArray stores key-value (KV) pairs. Each key must be unique, be of the number type, and have only one value.
PlainArray is based on generics and uses a lightweight structure. Keys in the array are searched using binary search and are mapped to values in other arrays.
Both PlainArray and LightWeightMap are used to store KV pairs in the lightweight structure. However, the key type of PlainArray can only be number.
Recommended use case: Use PlainArray when you need to store KV pairs whose keys are of the number type.
This topic uses the following to identify the use of generics: - T: Type
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 PlainArray from '@ohos.util.PlainArray';
PlainArray
Attributes
System capability: SystemCapability.Utils.Lang
| Name | Type | Readable | Writable | Description |
|---|---|---|---|---|
| length | number | Yes | No | Number of elements in a plain array (called container later). |
constructor
constructor()
A constructor used to create a PlainArray instance.
System capability: SystemCapability.Utils.Lang
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200012 | The PlainArray’s constructor cannot be directly invoked. |
Example
let plainArray: PlainArray<string> = new PlainArray();
isEmpty
isEmpty(): boolean
Checks whether this container is empty.
System capability: SystemCapability.Utils.Lang
Return value
| Type | Description |
|---|---|
| boolean | Returns true if the container is empty; returns false otherwise. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The isEmpty method cannot be bound. |
Example
const plainArray: PlainArray<string> = new PlainArray();
let result = plainArray.isEmpty();
has
has(key: number): boolean
Checks whether this container contains the specified key.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| key | number | Yes | Target key. |
Return value
| Type | Description |
|---|---|
| boolean | Returns true if the specified key is contained; returns false otherwise. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The has method cannot be bound. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
let result = plainArray.has(1);
get
get(key: number): T
Obtains the value of the specified key in this container.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| key | number | Yes | Target key. |
Return value
| Type | Description |
|---|---|
| T | Value of the key. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The get method cannot be bound. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let result = plainArray.get(1);
getIndexOfKey
getIndexOfKey(key: number): number
Obtains the index of the first occurrence of an element with the specified key in this container.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| key | number | Yes | Target key. |
Return value
| Type | Description |
|---|---|
| number | Returns the position index if obtained; returns -1 otherwise. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The getIndexOfKey method cannot be bound. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let result = plainArray.getIndexOfKey(2);
getIndexOfValue
getIndexOfValue(value: T): number
Obtains the index of the first occurrence of an element with the specified value in this container.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| value | T | Yes | Value of the target element. |
Return value
| Type | Description |
|---|---|
| number | Returns the position index if obtained; returns -1 otherwise. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The getIndexOfValue method cannot be bound. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let result = plainArray.getIndexOfValue("squirrel");
getKeyAt
getKeyAt(index: number): number
Obtains the key of the element at the specified position in this container.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| index | number | Yes | Position index of the target element. |
Return value
| Type | Description |
|---|---|
| number | Returns the key of the element if obtained; returns -1 otherwise. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The getKeyAt method cannot be bound. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let result = plainArray.getKeyAt(1);
getValueAt
getValueAt(index: number): T
Obtains the value of an element at the specified position in this container.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| index | number | Yes | Position index of the target element. |
Return value
| Type | Description |
|---|---|
| T | Returns the value of the element if obtained; returns undefined otherwise. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The getValueAt method cannot be bound. |
| 10200001 | The value of index is out of range. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let result = plainArray.getValueAt(1);
clone
clone(): PlainArray<T>
Clones this container and returns a copy. The modification to the copy does not affect the original instance.
System capability: SystemCapability.Utils.Lang
Return value
| Type | Description |
|---|---|
| PlainArray<T> | New PlainArray instance obtained. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The clone method cannot be bound. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let newPlainArray = plainArray.clone();
add
add(key: number, value: T): void
Adds an element to this container.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| key | number | Yes | Key of the target element. |
| value | T | Yes | Value of the target element. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The add method cannot be bound. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
remove
remove(key: number): T
Removes an element with the specified key from this container.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| key | number | Yes | Target key. |
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 plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let result = plainArray.remove(2);
removeAt
removeAt(index: number): T
Removes an element at the specified position from this container.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| index | number | Yes | Position index of the target element. |
Return value
| Type | Description |
|---|---|
| T | Element removed. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The removeAt method cannot be bound. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let result = plainArray.removeAt(1);
removeRangeFrom
removeRangeFrom(index: number, size: number): number
Removes elements in a specified range from this container.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| index | number | Yes | Start position of the elements to remove. |
| size | number | Yes | Number of elements to remove. |
Return value
| Type | Description |
|---|---|
| number | Number of elements removed. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The removeRangeFrom method cannot be bound. |
| 10200001 | The value of index is out of range. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let result = plainArray.removeRangeFrom(1, 3);
setValueAt
setValueAt(index: number, value: T): void
Sets a value for an element at the specified position in this container.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| index | number | Yes | Position index of the target element. |
| value | T | Yes | Value of the target element. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The setValueAt method cannot be bound. |
| 10200001 | The value of index is out of range. |
Example
let plainArray: PlainArray<string|number> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
plainArray.setValueAt(1, 3546);
toString
toString(): String
Obtains a string that contains all elements in this container.
System capability: SystemCapability.Utils.Lang
Return value
| Type | Description |
|---|---|
| String | String obtained. |
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The toString method cannot be bound. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let result = plainArray.toString();
clear
clear(): void
Clears this container and sets its length to 0.
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 plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
plainArray.clear();
forEach
forEach(callbackFn: (value: T, index?: number, PlainArray?: PlainArray<T>) => void, thisArg?: Object): void
Uses a callback to traverse the elements in this container and obtain their position indexes.
System capability: SystemCapability.Utils.Lang
Parameters
| Name | Type | Mandatory | Description |
|---|---|---|---|
| callbackFn | function | Yes | Callback invoked to traverse the elements in the container. |
| thisArg | Object | No | Value of this to use when callbackFn is invoked. The default value is this instance. |
callbackFn |Name|Type|Mandatory|Description| |——–|——–|——–|——–| |value|T|Yes|Value of the element that is currently traversed.| |index|number|No|Position index of the element that is currently traversed. The default value is 0.| |PlainArray|PlainArray<T>|No|Instance that calls the forEach API. The default value is this instance.|
Error codes
For details about the error codes, see Utils Error Codes.
| ID | Error Message |
|---|---|
| 10200011 | The forEach method cannot be bound. |
Example
let plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
plainArray.forEach((value: string, index?: number) => {
console.log("value:" + value, "index:" + index);
});
[Symbol.iterator]
[Symbol.iterator](): IterableIterator<[number, T]>
Obtains an iterator object that contains key-value pairs, where the key is of the number type.
System capability: SystemCapability.Utils.Lang
Return value
| Type | Description |
|---|---|
| IterableIterator<[number, 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 plainArray: PlainArray<string> = new PlainArray();
plainArray.add(1, "squirrel");
plainArray.add(2, "sparrow");
let iter = plainArray[Symbol.iterator]();
let temp: IteratorResult<Object[]> = iter.next();
while(!temp.done) {
console.log("key:" + temp.value[0]);
console.log("value:" + temp.value[1]);
temp = iter.next();
}
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