ApplicationStateObserver (System API)

The ApplicationStateObserver module defines an observer to listen for application state changes. It can be used as an input parameter in registerApplicationStateObserver to listen for lifecycle changes of the current application.

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. The APIs provided by this module are system APIs.

Modules to Import

import appManager from '@ohos.app.ability.appManager';

Attributes

System API: This is a system API and cannot be called by third-party applications.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name	Type	Readable	Writable	Description
onForegroundApplicationChanged	AsyncCallback<void>	Yes	No	Callback invoked when the foreground or background state of an application changes. The parameter type passed in is AppStateData.
onAbilityStateChanged	AsyncCallback<void>	Yes	No	Callback invoked when the ability state changes. The parameter type passed in is AbilityStateData.
onProcessCreated	AsyncCallback<void>	Yes	No	Callback invoked when a process is created. The parameter type passed in is ProcessData.
onProcessDied	AsyncCallback<void>	Yes	No	Callback invoked when a process is destroyed. The parameter type passed in is ProcessData.
onProcessStateChanged⁹⁺	AsyncCallback<void>	Yes	No	Callback invoked when the process state is changed. The parameter type passed in is ProcessData.

Example

import appManager from '@ohos.app.ability.appManager';

let applicationStateObserver: appManager.ApplicationStateObserver = {
    onForegroundApplicationChanged(appStateData) {
        console.log(`onForegroundApplicationChanged appStateData: ${JSON.stringify(appStateData)}`);
    },
    onAbilityStateChanged(abilityStateData) {
        console.log(`onAbilityStateChanged onAbilityStateChanged: ${JSON.stringify(abilityStateData)}`);
    },
    onProcessCreated(processData) {
        console.log(`onProcessCreated onProcessCreated: ${JSON.stringify(processData)}`);
    },
    onProcessDied(processData) {
        console.log(`onProcessDied onProcessDied: ${JSON.stringify(processData)}`);
    },
    onProcessStateChanged(processData) {
        console.log(`onProcessStateChanged onProcessStateChanged: ${JSON.stringify(processData)}`);
    }
};
let observerCode = appManager.on('applicationState', applicationStateObserver);