Nonlinear Container PlainArray
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.
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, which map 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.
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
Example
let plainArray = 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. |
Example
const plainArray = 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. |
Example
let plainArray = new PlainArray();
plainArray.has(1);
plainArray.add(1, "sddfhf");
let result1 = 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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
let result = plainArray.getIndexOfValue("sddfhf");
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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
let result = plainArray.getKeyAt(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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
plainArray.remove(2);
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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
plainArray.removeAt(1);
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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
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. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
let result = plainArray.toString();
clear
clear(): void
Clears this container and sets its length to 0.
System capability: SystemCapability.Utils.Lang
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
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 to use when the callback is invoked. |
callbackfn
Name | Type | Mandatory | Description |
---|---|---|---|
value | T | Yes | Value of the element that is currently traversed. |
index | number | No | Key of the element that is currently traversed. |
PlainArray | PlainArray<T> | No | Instance that invokes the forEach API. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
plainArray.forEach((value, index) => {
console.log("value:" + value, "index:" + index);
});
[Symbol.iterator]
[Symbol.iterator](): IterableIterator<[number, T]>
Obtains an iterator, each item of which is a JavaScript object.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
IterableIterator<[number, T]> | Iterator obtained. |
Example
let plainArray = new PlainArray();
plainArray.add(1, "sddfhf");
plainArray.add(2, "sffdfhf");
// Method 1:
for (let item of plainArray) {
console.log("index:" + item[0]);
console.log("value:" + item[1]);
}
// Method 2:
let iter = plainArray[Symbol.iterator]();
let temp = iter.next().value;
while(temp != undefined) {
console.log("index:" + temp[0]);
console.log("value:" + temp[1]);
temp = iter.next().value;
}