@ohos.systemTimer (System Timer)

The systemTimer module provides system timer features. You can use the APIs of this module to implement the alarm clock and other timer services.

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.
• The APIs provided by this module are system APIs.

Modules to Import

import systemTimer from '@ohos.systemTimer';

Constants

Provides the constants that define the supported timer types.

System capability: SystemCapability.MiscServices.Time

Name	Type	Value	Description
TIMER_TYPE_REALTIME	number	1	CPU time type. (The start time of the timer cannot be later than the current system time.)
TIMER_TYPE_WAKEUP	number	2	Wakeup type.
TIMER_TYPE_EXACT	number	4	Exact type.
TIMER_TYPE_IDLE	number	8	Idle type (not supported currently).

TimerOptions

Defines the initialization options for createTimer.

System capability: SystemCapability.MiscServices.Time

Name	Type	Mandatory	Description
type	number	Yes	Timer type. 1: CPU time type. (The start time of the timer cannot be later than the current system time.) 2: wakeup type. 4: exact type. 8: idle type (not supported currently).
repeat	boolean	Yes	Whether the timer is a repeating timer. The value true means that the timer is a repeating timer, and false means that the timer is a one-shot timer.
interval	number	No	Repeat interval. For a repeating timer, the value must be greater than 5000 ms. For a one-shot timer, the value is 0.
wantAgent	WantAgent	No	WantAgent object of the notification to be sent when the timer expires. (An application MainAbility can be started, but not a Service ability.)
callback	number	Yes	Callback used to return the timer ID.

systemTimer.createTimer

createTimer(options: TimerOptions, callback: AsyncCallback<number>): void

Creates a timer. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.MiscServices.Time

Parameters

Name	Type	Mandatory	Description
options	TimerOptions	Yes	Timer initialization options, including the timer type, whether the timer is a repeating timer, interval, and WantAgent options.
callback	AsyncCallback<number>	Yes	Callback used to return the timer ID.

Example

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

let options: systemTimer.TimerOptions = {
  type: systemTimer.TIMER_TYPE_REALTIME,
  repeat: false
};
try {
  systemTimer.createTimer(options, (error: BusinessError, timerId: Number) => {
    if (error) {
      console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
      return;
    }
    console.info(`Succeeded in creating a timer. timerId: ${timerId}`);
  });
} catch(e) {
  let error = e as BusinessError;
  console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
}

systemTimer.createTimer

createTimer(options: TimerOptions): Promise<number>

Creates a timer. This API uses a promise to return the result.

System capability: SystemCapability.MiscServices.Time

Parameters

Name	Type	Mandatory	Description
options	TimerOptions	Yes	Timer initialization options, including the timer type, whether the timer is a repeating timer, interval, and WantAgent options.

Return value

Type	Description
Promise<number>	Promise used to return the timer ID.

Example

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

let options: systemTimer.TimerOptions = {
  type: systemTimer.TIMER_TYPE_REALTIME,
  repeat:false
};
try {
  systemTimer.createTimer(options).then((timerId: Number) => {
    console.info(`Succeeded in creating a timer. timerId: ${timerId}`);
  }).catch((error: BusinessError) => {
    console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
  });
} catch(e) {
  let error = e as BusinessError;
  console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
}

systemTimer.startTimer

startTimer(timer: number, triggerTime: number, callback: AsyncCallback<void>): void

Starts a timer. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.MiscServices.Time

Parameters

Name	Type	Mandatory	Description
timer	number	Yes	ID of the timer.
triggerTime	number	Yes	Time when the timer is triggered, in milliseconds.
callback	AsyncCallback<void>	Yes	Callback used to return the result.

Example

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

let options: systemTimer.TimerOptions = {
  type: systemTimer.TIMER_TYPE_REALTIME,
  repeat:false
}
let triggerTime = new Date().getTime();
triggerTime += 3000;

try {
  systemTimer.createTimer(options).then((timerId: number) => {
    systemTimer.startTimer(timerId, triggerTime, (error: BusinessError) => {
      if (error) {
        console.info(`Failed to start the timer. Message: ${error.message}, code: ${error.code}`);
        return;
      }
      console.info(`Succeeded in starting the timer.`);
    });
    console.info(`Succeeded in creating a timer. timerId: ${timerId}`);
  }).catch((error: BusinessError) => {
    console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
  });
} catch(e) {
  let error = e as BusinessError;
  console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
}

systemTimer.startTimer

startTimer(timer: number, triggerTime: number): Promise<void>

Starts a timer. This API uses a promise to return the result.

System capability: SystemCapability.MiscServices.Time

Parameters

Name	Type	Mandatory	Description
timer	number	Yes	ID of the timer.
triggerTime	number	Yes	Time when the timer is triggered, in milliseconds.

Return value

Type	Description
Promise<void>	Promise that returns no value.

Example

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

let options: systemTimer.TimerOptions = {
  type: systemTimer.TIMER_TYPE_REALTIME,
  repeat:false
}
let triggerTime = new Date().getTime();
triggerTime += 3000;

try {
  systemTimer.createTimer(options).then((timerId: number) => {
    systemTimer.startTimer(timerId, triggerTime).then(() => {
      console.info(`Succeeded in starting the timer.`);
    }).catch((error: BusinessError) => {
      console.info(`Failed to start the timer. Message: ${error.message}, code: ${error.code}`);
    });
    console.info(`Succeeded in creating a timer. timerId: ${timerId}`);
  }).catch((error: BusinessError) => {
    console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
  });
} catch(e) {
  let error = e as BusinessError;
  console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
}

systemTimer.stopTimer

stopTimer(timer: number, callback: AsyncCallback<void>): void

Stops a timer. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.MiscServices.Time

Parameters

Name	Type	Mandatory	Description
timer	number	Yes	ID of the timer.
callback	AsyncCallback<void>	Yes	Callback used to return the result.

Example

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

let options: systemTimer.TimerOptions = {
  type: systemTimer.TIMER_TYPE_REALTIME,
  repeat:false
}
let triggerTime = new Date().getTime();
triggerTime += 3000;

try {
  systemTimer.createTimer(options).then((timerId: number) => {
    systemTimer.startTimer(timerId, triggerTime);
    systemTimer.stopTimer(timerId, (error: BusinessError) => {
      if (error) {
        console.info(`Failed to stop the timer. Message: ${error.message}, code: ${error.code}`);
        return;
      }
    console.info(`Succeeded in stopping the timer.`);
    });
    console.info(`Succeeded in creating a timer. timerId: ${timerId}`);
  }).catch((error: BusinessError) => {
    console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
  });
} catch(e) {
  let error = e as BusinessError;
  console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
}

systemTimer.stopTimer

stopTimer(timer: number): Promise<void>

Stops a timer. This API uses a promise to return the result.

System capability: SystemCapability.MiscServices.Time

Parameters

Name	Type	Mandatory	Description
timer	number	Yes	ID of the timer.

Return value

Type	Description
Promise<void>	Promise that returns no value.

Example

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

let options: systemTimer.TimerOptions = {
  type: systemTimer.TIMER_TYPE_REALTIME,
  repeat:false
}
let triggerTime = new Date().getTime();
triggerTime += 3000;

try {
  systemTimer.createTimer(options).then((timerId: number) => {
    systemTimer.startTimer(timerId, triggerTime);
    systemTimer.stopTimer(timerId).then(() => {
      console.info(`Succeeded in stopping the timer.`);
    }).catch((error: BusinessError) => {
      console.info(`Failed to stop the timer. Message: ${error.message}, code: ${error.code}`);
    });
    console.info(`Succeeded in creating a timer. timerId: ${timerId}`);
  }).catch((error: BusinessError) => {
    console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
  });
} catch(e) {
  let error = e as BusinessError;
  console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
}

systemTimer.destroyTimer

destroyTimer(timer: number, callback: AsyncCallback<void>): void

Destroys a timer. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.MiscServices.Time

Parameters

Name	Type	Mandatory	Description
timer	number	Yes	ID of the timer.
callback	AsyncCallback<void>	Yes	Callback used to return the result.

Example

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

let options: systemTimer.TimerOptions = {
  type: systemTimer.TIMER_TYPE_REALTIME,
  repeat:false
}
let triggerTime = new Date().getTime();
triggerTime += 3000;

try {
  systemTimer.createTimer(options).then((timerId: number) => {
    systemTimer.startTimer(timerId, triggerTime);
    systemTimer.stopTimer(timerId);
    systemTimer.destroyTimer(timerId, (error: BusinessError) => {
      if (error) {
        console.info(`Failed to destroy the timer. Message: ${error.message}, code: ${error.code}`);
        return;
      }
    console.info(`Succeeded in destroying the timer.`);
    });
    console.info(`Succeeded in creating a timer. timerId: ${timerId}`);
  }).catch((error: BusinessError) => {
    console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
  });
} catch(e) {
  let error = e as BusinessError;
  console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
}

systemTimer.destroyTimer

destroyTimer(timer: number): Promise<void>

Destroys a timer. This API uses a promise to return the result.

System capability: SystemCapability.MiscServices.Time

Parameters

Name	Type	Mandatory	Description
timer	number	Yes	ID of the timer.

Return value

Type	Description
Promise<void>	Promise that returns no value.

Example

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

let options: systemTimer.TimerOptions = {
  type: systemTimer.TIMER_TYPE_REALTIME,
  repeat:false
}
let triggerTime = new Date().getTime();
triggerTime += 3000;

try {
  systemTimer.createTimer(options).then((timerId: number) => {
    systemTimer.startTimer(timerId, triggerTime);
    systemTimer.stopTimer(timerId);
    systemTimer.destroyTimer(timerId).then(() => {
      console.info(`Succeeded in destroying the timer.`);
    }).catch((error: BusinessError) => {
      console.info(`Failed to destroy the timer. Message: ${error.message}, code: ${error.code}`);
    });
    console.info(`Succeeded in creating a timer. timerId: ${timerId}`);
  }).catch((error: BusinessError) => {
    console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
  });
} catch(e) {
  let error = e as BusinessError;
  console.info(`Failed to create a timer. Message: ${error.message}, code: ${error.code}`);
}

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