harmony 鸿蒙@ohos.util.Stack (Linear Container Stack)
@ohos.util.Stack (Linear Container Stack)
Stack is implemented based on the array data structure. It follows the principle Last Out First In (LOFI) and supports data insertion and removal at one end.
Unlike Queue, which is implemented based on the queue data structure and supports insertion at one end and removal at the other end, Stack supports insertion and removal at the same end.
Recommended use case: Use Stack in LOFI scenarios.
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 Stack from '@ohos.util.Stack';
Stack
Attributes
System capability: SystemCapability.Utils.Lang
Name | Type | Readable | Writable | Description |
---|---|---|---|---|
length | number | Yes | No | Number of elements in a stack (called container later). |
constructor
constructor()
A constructor used to create a Stack instance.
System capability: SystemCapability.Utils.Lang
Error codes
For details about the error codes, see Utils Error Codes.
ID | Error Message |
---|---|
10200012 | The Stack’s constructor cannot be directly invoked. |
Example
let stack : Stack<number|string|Object> = new Stack();
push
push(item: T): T
Adds an element at the top of this container.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
item | T | Yes | Target element. |
Return value
Type | Description |
---|---|
T | Element added. |
Error codes
For details about the error codes, see Utils Error Codes.
ID | Error Message |
---|---|
10200011 | The push method cannot be bound. |
Example
class C1 {
name: string = ""
age: string = ""
}
let stack : Stack<number|string|C1> = new Stack();
let result = stack.push("a");
let result1 = stack.push(1);
let b = [1, 2, 3];
let result2 = stack.push(b);
let c : C1 = {name : "Dylon", age : "13"};
let result3 = stack.push(c);
pop
pop(): T
Removes the top element from this container.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
T | Element removed. |
Error codes
For details about the error codes, see Utils Error Codes.
ID | Error Message |
---|---|
10200011 | The pop method cannot be bound. |
Example
let stack : Stack<number> = new Stack();
stack.push(2);
stack.push(4);
stack.push(5);
stack.push(2);
stack.push(4);
let result = stack.pop();
peek
peek(): T
Obtains the top element of this container.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
T | Element obtained. |
Error codes
For details about the error codes, see Utils Error Codes.
ID | Error Message |
---|---|
10200011 | The peek method cannot be bound. |
Example
let stack : Stack<number> = new Stack();
stack.push(2);
stack.push(4);
stack.push(5);
stack.push(2);
let result = stack.peek();
locate
locate(element: T): number
Obtains the index of the first occurrence of the specified element in this container.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
element | T | Yes | 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 locate method cannot be bound. |
Example
let stack : Stack<number> = new Stack();
stack.push(2);
stack.push(4);
stack.push(5);
stack.push(2);
let result = stack.locate(2);
forEach
forEach(callbackFn: (value: T, index?: number, stack?: Stack<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. |
stack | Stack<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 stack : Stack<number> = new Stack();
stack.push(2);
stack.push(4);
stack.push(5);
stack.push(4);
stack.forEach((value : number, index ?: number) :void => {
console.log("value:" + value, "index:" + index);
});
isEmpty
isEmpty(): boolean
Checks whether this container is empty (contains no elements).
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
let stack : Stack<number> = new Stack();
stack.push(2);
stack.push(4);
stack.push(5);
stack.push(4);
let result = stack.isEmpty();
[Symbol.iterator]
[Symbol.iterator](): IterableIterator<T>
Obtains an iterator, each item of which is a JavaScript object.
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 stack : Stack<number> = new Stack();
stack.push(2);
stack.push(4);
stack.push(5);
stack.push(4);
// Method 1:
while(!stack.isEmpty()) {
// Service logic
let item = stack.pop()
console.log("value:" + item);
}
// Method 2:
let iter = stack[Symbol.iterator]();
let temp: IteratorResult<number> = iter.next().value;
while(temp != undefined) {
console.log("value:" + temp);
temp = iter.next().value;
}
你可能感兴趣的鸿蒙文章
harmony 鸿蒙System Common Events (To Be Deprecated Soon)
harmony 鸿蒙System Common Events
harmony 鸿蒙API Reference Document Description
harmony 鸿蒙Enterprise Device Management Overview (for System Applications Only)
harmony 鸿蒙BundleStatusCallback
harmony 鸿蒙@ohos.bundle.innerBundleManager (innerBundleManager)
harmony 鸿蒙@ohos.distributedBundle (Distributed Bundle Management)
harmony 鸿蒙@ohos.bundle (Bundle)
harmony 鸿蒙@ohos.enterprise.EnterpriseAdminExtensionAbility (EnterpriseAdminExtensionAbility)
- 所属分类: 后端技术
- 本文标签:
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
8、 golang
-
9、 openharmony
-
10、 Vue中input框自动聚焦