harmony 鸿蒙@ohos.app.ability.AbilityConstant (AbilityConstant)

  • 2022-12-22
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@ohos.app.ability.AbilityConstant (AbilityConstant)

The AbilityConstant module defines the ability-related enums, including the initial launch reasons, reasons for the last exit, ability continuation results, and window modes.

NOTE

The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version. The APIs of this module can be used only in the stage model.

Modules to Import

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

Attributes

AbilityConstant.LaunchParam

Defines the parameters for starting an ability.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name Type Readable Writable Description
launchReason LaunchReason Yes Yes Ability launch reason, which is an enumerated type.
lastExitReason LastExitReason Yes Yes Reason for the last exit, which is an enumerated type.

AbilityConstant.LaunchReason

Enumerates the initial ability launch reasons. You can use it together with onCreate(want, launchParam) of Ability to complete different operations.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name Value Description
UNKNOWN 0 Unknown reason.
START_ABILITY 1 The ability is started by calling startAbility.
CALL 2 The ability is started by calling startAbilityByCall.
CONTINUATION 3 The ability is started by means of cross-device migration.
APP_RECOVERY 4 The ability is automatically started when the application is restored from a fault.
SHARE10+ 5 The ability is started by means of atomic service sharing.

Example

import UIAbility from '@ohos.app.ability.UIAbility';
import Want from '@ohos.app.ability.Want';

class MyAbility extends UIAbility {
    onCreate(want: Want, launchParam: AbilityConstant.LaunchParam) {
        if (launchParam.launchReason === AbilityConstant.LaunchReason.START_ABILITY) {
            console.log('The ability has been started by the way of startAbility.');
        }
    }
}

AbilityConstant.LastExitReason

Enumerates the reasons for the last exit. You can use it together with onCreate(want, launchParam) of Ability to complete different operations.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name Value Description
UNKNOWN 0 Unknown reason.
ABILITY_NOT_RESPONDING 1 The ability does not respond. This enum is supported since API version 9 and deprecated since API version 10. You are advised to use APP_FREEZE.
NORMAL 2 The ability exits normally because the user closes the application.
CPP_CRASH10+ 3 The ability exits due to abnormal signals on the local host.
JS_ERROR10+ 4 The ability exits due to a JS_ERROR fault triggered when an application has a JS syntax error that is not captured by developers.
APP_FREEZE10+ 5 The ability exits because watchdog detects that the application is frozen.
PERFORMANCE_CONTROL10+ 6 The ability exits due to system performance problems, for example, insufficient device memory.
RESOURCE_CONTROL10+ 7 The ability exits because the system resource usage (CPU, I/O, or memory usage) exceeds the upper limit.
UPGRADE10+ 8 The ability exits due to an update.

Example

import UIAbility from '@ohos.app.ability.UIAbility';
import Want from '@ohos.app.ability.Want';

class MyAbility extends UIAbility {
    onCreate(want: Want, launchParam: AbilityConstant.LaunchParam) {
        if (launchParam.lastExitReason === AbilityConstant.LastExitReason.ABILITY_NOT_RESPONDING) {
            console.log('The ability has exit last because the ability was not responding.');
        }
    }
}

AbilityConstant.OnContinueResult

Enumerates the ability continuation results. You can use it together with onContinue(wantParam) of Ability to complete different operations.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name Value Description
AGREE 0 The ability continuation is accepted.
REJECT 1 The ability continuation is rejected. If the application is abnormal in onContinue, which results in abnormal display during data restoration, this error code is returned.
MISMATCH 2 The version does not match. The application on the initiator can obtain the version of the target application from onContinue. If the ability continuation cannot be performed due to version mismatch, this error code is returned.

Example

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

class MyAbility extends UIAbility {
    onContinue(wantParam: Record<string, Object>) {
        return AbilityConstant.OnContinueResult.AGREE;
    }
}

AbilityConstant.WindowMode

Enumerates the window modes in which an ability can be displayed at startup. It can be used in startAbility() to specify the window mode when the ability is started.

System capability: SystemCapability.Ability.AbilityRuntime.Core

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

Name Value Description
WINDOW_MODE_UNDEFINED 0 Undefined window mode.
WINDOW_MODE_FULLSCREEN 1 The ability is displayed in full screen.
WINDOW_MODE_SPLIT_PRIMARY 100 The left screen in horizontal direction or the upper screen in vertical direction is the primary window.
WINDOW_MODE_SPLIT_SECONDARY 101 The right screen in horizontal direction or the lower screen in vertical direction is the secondary window.
WINDOW_MODE_FLOATING 102 The ability is displayed in a floating window.

Example

import StartOptions from '@ohos.app.ability.StartOptions';
import Want from '@ohos.app.ability.Want';
import { BusinessError } from '@ohos.base';

let want: Want = {
    bundleName: 'com.example.myapplication',
    abilityName: 'EntryAbility'
};
let option: StartOptions = {
    windowMode: AbilityConstant.WindowMode.WINDOW_MODE_FULLSCREEN
};

// Ensure that the context is obtained.
this.context.startAbility(want, option).then(()=>{
    console.log('Succeed to start ability.');
}).catch((error: BusinessError)=>{
    console.error('Failed to start ability with error: ${JSON.stringify(error)}');
});

AbilityConstant.MemoryLevel

Enumerates the memory levels. You can use it in onMemoryLevel(level) of Ability to complete different operations.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name Value Description
MEMORY_LEVEL_MODERATE 0 Moderate memory usage.
MEMORY_LEVEL_LOW 1 Low memory usage.
MEMORY_LEVEL_CRITICAL 2 High memory usage.

Example

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

class MyAbility extends UIAbility {
    onMemoryLevel(level: AbilityConstant.MemoryLevel) {
        if (level === AbilityConstant.MemoryLevel.MEMORY_LEVEL_CRITICAL) {
            console.log('The memory of device is critical, please release some memory.');
        }
    }
}

AbilityConstant.OnSaveResult

Enumerates the result types for the operation of saving application data. You can use it in onSaveState(reason, wantParam) of Ability to complete different operations.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name Value Description
ALL_AGREE 0 Always agreed to save the status.
CONTINUATION_REJECT 1 Rejected to save the status in continuation.
CONTINUATION_MISMATCH 2 Continuation mismatch.
RECOVERY_AGREE 3 Agreed to restore the saved status.
RECOVERY_REJECT 4 Rejected to restore the saved state.
ALL_REJECT 5 Always rejected to save the status.

Example

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

class MyAbility extends UIAbility {
    onSaveState(reason: AbilityConstant.StateType, wantParam: Record<string, Object>) {
        return AbilityConstant.OnSaveResult.ALL_AGREE;
    }
}

AbilityConstant.StateType

Enumerates the scenarios for saving application data. You can use it in onSaveState(reason, wantParam) of Ability to complete different operations.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name Value Description
CONTINUATION 0 Saving the status in continuation.
APP_RECOVERY 1 Saving the status in application recovery.

Example

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

class MyAbility extends UIAbility {
    onSaveState(reason: AbilityConstant.StateType, wantParam: Record<string, Object>) {
        if (reason === AbilityConstant.StateType.CONTINUATION) {
            console.log('Save the ability data when the ability continuation.');
        } 
        return AbilityConstant.OnSaveResult.ALL_AGREE;
    }
}

AbilityConstant.ContinueState10+

Enumerates the mission continuation states of the application. It is used in the setMissionContinueState API of UIAbilityContext.

System capability: SystemCapability.Ability.AbilityRuntime.Core

Name Value Description
ACTIVE 0 Mission continuation is activated for the current application.
INACTIVE 1 Mission continuation is not activated for the current application.

Example

  import { BusinessError } from '@ohos.base';

  this.context.setMissionContinueState(AbilityConstant.ContinueState.INACTIVE, (result: BusinessError) => {
    console.info(`setMissionContinueState: ${JSON.stringify(result)}`);
  });

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