harmony 鸿蒙State Management with Application-level Variables (System API)

2025-06-12
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State Management with Application-level Variables (System API)

The state management module provides data storage, persistent data management, UIAbility data storage, and environment state required by applications.

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.

This topic describes only the system APIs provided by the module. For details about its public APIs, see State Management with Application-level Variables.

SubscribedAbstractProperty<T>

Widget capability: This API can be used in ArkTS widgets since API version 9.

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.ArkUI.ArkUI.Full

subscribers_

protected subscribers_: Set<number>;

A set of subscribers.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

Type	Description
Set<number>	A set of subscribers.

id_

private id_;

Private member variable ID.

System capability: SystemCapability.ArkUI.ArkUI.Full

info_

private info_\?;

Variable information.

System capability: SystemCapability.ArkUI.ArkUI.Full

constructor

constructor(subscribeMe?: IPropertySubscriber,info?: string,);

Constructor.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
subscribeMe	IPropertySubscriber	No	Variable properties.
info	string	No	Variable information.

id

id(): number;

Obtains the ID.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

Type	Description
number	Obtained ID.

createTwoWaySync

createTwoWaySync(subscribeMe?: IPropertySubscriber, info?: string): SyncedPropertyTwoWay<T>;

Creates two-way synchronization.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
subscribeMe	IPropertySubscriber	No	Variable properties.
info	string	No	Variable information.

Return value

Type	Description
SyncedPropertyTwoWay<T>	Two-way synchronized property.

createOneWaySync

createOneWaySync(subscribeMe?: IPropertySubscriber, info?: string): SyncedPropertyOneWay<T>;

Creates one-way synchronization.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
subscribeMe	IPropertySubscriber	No	Variable properties.
info	string	No	Variable information.

Return value

Type	Description
SyncedPropertyOneWay<T>	One-way synchronized property.

unlinkSuscriber

unlinkSuscriber(subscriberId: number): void;

Removes a subscriber.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
subscriberId	number	Yes	ID of the subscriber to remove.

notifyHasChanged

protected notifyHasChanged(newValue: T): void;

Notifies subscribers that the value has changed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
newValue	T	Yes	New value after the change.

notifyPropertyRead

protected notifyPropertyRead(): void;

Notifies subscribers that the property has been read.

System capability: SystemCapability.ArkUI.ArkUI.Full

numberOfSubscrbers

numberOfSubscrbers(): number;

Obtains the number of subscribers.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

Type	Description
number	Number of subscribers.

IPropertySubscriber

System capability: SystemCapability.ArkUI.ArkUI.Full

id

id(): number;

Obtains the ID.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

Type	Description
number	Variable ID obtained.

aboutToBeDeleted

aboutToBeDeleted(owningView?: IPropertySubscriber): void;

Called when the object is about to be destroyed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
owningView	IPropertySubscriber	No	Component that owns the current property.

SyncedPropertyTwoWay<T>

Inherits from SubscribedAbstractProperty<T>. Represents a property with two-way synchronization.

System capability: SystemCapability.ArkUI.ArkUI.Full

source_

private source_;

Data source for the two-way synchronized property.

System capability: SystemCapability.ArkUI.ArkUI.Full

constructor

constructor(source: SubscribedAbstractProperty<T>, subscribeMe?: IPropertySubscriber, info?: string);

Constructor.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
source	SubscribedAbstractProperty<T>	Yes	Data source for the two-way synchronized property.
subscribeMe	IPropertySubscriber	No	Subscriber.
info	string	No	Additional information about the subscriber.

aboutToBeDeleted

aboutToBeDeleted(unsubscribeMe?: IPropertySubscriber): void;

Called when the object is about to be destroyed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
unsubscribeMe	IPropertySubscriber	No	Subscriber to remove.

hasChanged

hasChanged(newValue: T): void;

Notifies subscribers that the property value has changed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
newValue	T	Yes	New value of the property.

get

get(): T;

Obtains the current value of the property.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

Type	Description
T	Current value of the property.

set

set(newValue: T): void;

Sets a new value for the property.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
newValue	T	Yes	New value to set for the property.

SyncedPropertyOneWay<T>

Inherits from SubscribedAbstractProperty<T>. Represents a property with one-way synchronization.

System capability: SystemCapability.ArkUI.ArkUI.Full

wrappedValue_

private wrappedValue_;

Value used for one-way binding.

System capability: SystemCapability.ArkUI.ArkUI.Full

source_

private source_;

Data source for the one-way synchronized property.

System capability: SystemCapability.ArkUI.ArkUI.Full

constructor

constructor(source: SubscribedAbstractProperty<T>, subscribeMe?: IPropertySubscriber, info?: string);

Constructor.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
source	SubscribedAbstractProperty<T>	Yes	Data source for the one-way synchronized property.
subscribeMe	IPropertySubscriber	No	Subscriber.
info	string	No	Additional information of the subscriber.

aboutToBeDeleted

aboutToBeDeleted(unsubscribeMe?: IPropertySubscriber): void;

Called when the object is about to be destroyed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
unsubscribeMe	IPropertySubscriber	No	Subscriber to remove.

hasChanged

hasChanged(newValue: T): void;

Notifies subscribers that the property value has changed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
newValue	T	Yes	New value of the property.

get

get(): T;

Obtains the current value of the property.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

Type	Description
T	Current value of the property.

set

set(newValue: T): void;

Sets a new value for the property.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
newValue	T	Yes	New value to set for the property.

ISinglePropertyChangeSubscriber<T>

Inherits from IPropertySubscriber. Represents a subscriber that subscribes to changes in a property value.

System capability: SystemCapability.ArkUI.ArkUI.Full

hasChanged

hasChanged(newValue: T): void;

Notifies subscribers that the property value has changed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
newValue	T	Yes	New value of the property.

SubscribaleAbstract

System capability: SystemCapability.ArkUI.ArkUI.Full

owningProperties_

private owningProperties_: Set<number>;

A set of property IDs that this instance owns.

System capability: SystemCapability.ArkUI.ArkUI.Full

Return value

Type	Description
Set<number>	A set of property IDs.

constructor

constructor();

Constructor.

System capability: SystemCapability.ArkUI.ArkUI.Full

notifyPropertyHasChanged

protected notifyPropertyHasChanged(propName: string, newValue: any): void;

Notify subscribers that a property value has changed.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
propName	string	Yes	Property name.
newValue	any	No	New value after the change.

addOwningProperty

public addOwningProperty(subscriber: IPropertySubscriber): void;

Adds a subscriber to the list of owned properties.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
subscriber	IPropertySubscriber	Yes	Subscriber.

removeOwningProperty

public removeOwningProperty(property: IPropertySubscriber): void;

Removes a subscriber from the list of owned properties.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
property	IPropertySubscriber	Yes	Subscriber to remove.

removeOwningPropertyById

public removeOwningPropertyById(subscriberId: number): void;

Removes a subscriber from the list of owned properties by ID.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
subscriberId	number	Yes	ID of the subscriber to remove.

Environment

System capability: SystemCapability.ArkUI.ArkUI.Full

constructor

constructor();

Constructor.

System capability: SystemCapability.ArkUI.ArkUI.Full

PersistentStorage

Atomic service API: This API can be used in atomic services since API version 11.

System capability: SystemCapability.ArkUI.ArkUI.Full

constructor

constructor(appStorage: AppStorage, storage: Storage);

Constructor.

System capability: SystemCapability.ArkUI.ArkUI.Full

Parameters

Name	Type	Mandatory	Description
appStorage	AppStorage	Yes	Application-level storage.
storage	Storage	Yes	Storage.

appStorage

declare const appStorage: AppStorage;

Defines the application-level storage.

System capability: SystemCapability.ArkUI.ArkUI.Full

Type	Description
AppStorage	Application-level storage.

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harmony 鸿蒙State Management with Application-level Variables (System API)

State Management with Application-level Variables (System API)

SubscribedAbstractProperty<T>

subscribers_

id_

info_

constructor

id

createTwoWaySync

createOneWaySync

unlinkSuscriber

notifyHasChanged

notifyPropertyRead

numberOfSubscrbers

IPropertySubscriber

id

aboutToBeDeleted

SyncedPropertyTwoWay<T>

source_

constructor

aboutToBeDeleted

hasChanged

get

set

SyncedPropertyOneWay<T>

wrappedValue_

source_

constructor

aboutToBeDeleted

hasChanged

get

set

ISinglePropertyChangeSubscriber<T>

hasChanged

SubscribaleAbstract

owningProperties_

constructor

notifyPropertyHasChanged

addOwningProperty

removeOwningProperty

removeOwningPropertyById

Environment

constructor

PersistentStorage

constructor

appStorage

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