AlarmManager类api
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AlarmManager
public class AlarmManager
extends Object
This class provides access to the system alarm services. These allow you to schedule your application to be run at some point in the future. When an alarm goes off, the Intent
that had been registered for it is broadcast by the system, automatically starting the target application if it is not already running. Registered alarms are retained while the device is asleep (and can optionally wake the device up if they go off during that time), but will be cleared if it is turned off and rebooted.
The Alarm Manager holds a CPU wake lock as long as the alarm receiver’s onReceive() method is executing. This guarantees that the phone will not sleep until you have finished handling the broadcast. Once onReceive() returns, the Alarm Manager releases this wake lock. This means that the phone will in some cases sleep as soon as your onReceive() method completes. If your alarm receiver called Context.startService()
, it is possible that the phone will sleep before the requested service is launched. To prevent this, your BroadcastReceiver and Service will need to implement a separate wake lock policy to ensure that the phone continues running until the service becomes available.
Note: The Alarm Manager is intended for cases where you want to have your application code run at a specific time, even if your application is not currently running. For normal timing operations (ticks, timeouts, etc) it is easier and much more efficient to use Handler
.
Note: Beginning with API 19 (KITKAT
) alarm delivery is inexact: the OS will shift alarms in order to minimize wakeups and battery use. There are new APIs to support applications which need strict delivery guarantees; see setWindow(int, long, long, PendingIntent)
and setExact(int, long, PendingIntent)
. Applications whose targetSdkVersion
is earlier than API 19 will continue to see the previous behavior in which all alarms are delivered exactly when requested.
You do not instantiate this class directly; instead, retrieve it through Context.getSystemService(Context.ALARM_SERVICE)
.
Summary
Nested classes
class
AlarmManager.AlarmClockInfo
An immutable description of a scheduled “alarm clock” event.
interface
AlarmManager.OnAlarmListener
Direct-notification alarms: the requester must be running continuously from the time the alarm is set to the time it is delivered, or delivery will fail.
Constants
String
ACTION_NEXT_ALARM_CLOCK_CHANGED
Broadcast Action: Sent after the value returned by getNextAlarmClock()
has changed.
int
ELAPSED_REALTIME
Alarm time in SystemClock.elapsedRealtime()
(time since boot, including sleep).
int
ELAPSED_REALTIME_WAKEUP
Alarm time in SystemClock.elapsedRealtime()
(time since boot, including sleep), which will wake up the device when it goes off.
long
INTERVAL_DAY
Available inexact recurrence interval recognized by setInexactRepeating(int, long, long, PendingIntent)
when running on Android prior to API 19.
long
INTERVAL_FIFTEEN_MINUTES
Available inexact recurrence interval recognized by setInexactRepeating(int, long, long, PendingIntent)
when running on Android prior to API 19.
long
INTERVAL_HALF_DAY
Available inexact recurrence interval recognized by setInexactRepeating(int, long, long, PendingIntent)
when running on Android prior to API 19.
long
INTERVAL_HALF_HOUR
Available inexact recurrence interval recognized by setInexactRepeating(int, long, long, PendingIntent)
when running on Android prior to API 19.
long
INTERVAL_HOUR
Available inexact recurrence interval recognized by setInexactRepeating(int, long, long, PendingIntent)
when running on Android prior to API 19.
int
RTC
Alarm time in System.currentTimeMillis()
(wall clock time in UTC).
int
RTC_WAKEUP
Alarm time in System.currentTimeMillis()
(wall clock time in UTC), which will wake up the device when it goes off.
Public methods
void
cancel(PendingIntent operation)
Remove any alarms with a matching Intent
.
void
cancel(AlarmManager.OnAlarmListener listener)
Remove any alarm scheduled to be delivered to the given AlarmManager.OnAlarmListener
.
AlarmManager.AlarmClockInfo
getNextAlarmClock()
Gets information about the next alarm clock currently scheduled.
void
set(int type, long triggerAtMillis, PendingIntent operation)
Schedule an alarm.
void
set(int type, long triggerAtMillis, String tag, AlarmManager.OnAlarmListener listener, Handler targetHandler)
Direct callback version of set(int, long, PendingIntent)
.
void
setAlarmClock(AlarmManager.AlarmClockInfo info, PendingIntent operation)
Schedule an alarm that represents an alarm clock.
void
setAndAllowWhileIdle(int type, long triggerAtMillis, PendingIntent operation)
Like set(int, long, PendingIntent)
, but this alarm will be allowed to execute even when the system is in low-power idle modes.
void
setExact(int type, long triggerAtMillis, PendingIntent operation)
Schedule an alarm to be delivered precisely at the stated time.
void
setExact(int type, long triggerAtMillis, String tag, AlarmManager.OnAlarmListener listener, Handler targetHandler)
Direct callback version of setExact(int, long, PendingIntent)
.
void
setExactAndAllowWhileIdle(int type, long triggerAtMillis, PendingIntent operation)
Like setExact(int, long, PendingIntent)
, but this alarm will be allowed to execute even when the system is in low-power idle modes.
void
setInexactRepeating(int type, long triggerAtMillis, long intervalMillis, PendingIntent operation)
Schedule a repeating alarm that has inexact trigger time requirements; for example, an alarm that repeats every hour, but not necessarily at the top of every hour.
void
setRepeating(int type, long triggerAtMillis, long intervalMillis, PendingIntent operation)
Schedule a repeating alarm.
void
setTime(long millis)
Set the system wall clock time.
void
setTimeZone(String timeZone)
Sets the system’s persistent default time zone.
void
setWindow(int type, long windowStartMillis, long windowLengthMillis, PendingIntent operation)
Schedule an alarm to be delivered within a given window of time.
void
setWindow(int type, long windowStartMillis, long windowLengthMillis, String tag, AlarmManager.OnAlarmListener listener, Handler targetHandler)
Direct callback version of setWindow(int, long, long, PendingIntent)
.
Inherited methods
java.lang.Object
Object
clone()
Creates and returns a copy of this object.
boolean
equals(Object obj)
Indicates whether some other object is “equal to” this one.
void
finalize()
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
final Class<?>
getClass()
Returns the runtime class of this Object
.
int
hashCode()
Returns a hash code value for the object.
final void
notify()
Wakes up a single thread that is waiting on this object’s monitor.
final void
notifyAll()
Wakes up all threads that are waiting on this object’s monitor.
String
toString()
Returns a string representation of the object.
final void
wait(long millis, int nanos)
Causes the current thread to wait until another thread invokes the notify()
method or the notifyAll()
method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
final void
wait(long millis)
Causes the current thread to wait until either another thread invokes the notify()
method or the notifyAll()
method for this object, or a specified amount of time has elapsed.
final void
wait()
Causes the current thread to wait until another thread invokes the notify()
method or the notifyAll()
method for this object.
Constants
ACTION_NEXT_ALARM_CLOCK_CHANGED
String ACTION_NEXT_ALARM_CLOCK_CHANGED
Broadcast Action: Sent after the value returned by getNextAlarmClock()
has changed.
This is a protected intent that can only be sent by the system. It is only sent to registered receivers.
Constant Value: “android.app.action.NEXT_ALARM_CLOCK_CHANGED”
ELAPSED_REALTIME
int ELAPSED_REALTIME
Alarm time in SystemClock.elapsedRealtime()
(time since boot, including sleep). This alarm does not wake the device up; if it goes off while the device is asleep, it will not be delivered until the next time the device wakes up.
Constant Value: 3 (0x00000003)
ELAPSED_REALTIME_WAKEUP
int ELAPSED_REALTIME_WAKEUP
Alarm time in SystemClock.elapsedRealtime()
(time since boot, including sleep), which will wake up the device when it goes off.
Constant Value: 2 (0x00000002)
INTERVAL_DAY
long INTERVAL_DAY
Available inexact recurrence interval recognized by setInexactRepeating(int, long, long, PendingIntent)
when running on Android prior to API 19.
Constant Value: 86400000 (0x0000000005265c00)
INTERVAL_FIFTEEN_MINUTES
long INTERVAL_FIFTEEN_MINUTES
Available inexact recurrence interval recognized by setInexactRepeating(int, long, long, PendingIntent)
when running on Android prior to API 19.
Constant Value: 900000 (0x00000000000dbba0)
INTERVAL_HALF_DAY
long INTERVAL_HALF_DAY
Available inexact recurrence interval recognized by setInexactRepeating(int, long, long, PendingIntent)
when running on Android prior to API 19.
Constant Value: 43200000 (0x0000000002932e00)
INTERVAL_HALF_HOUR
long INTERVAL_HALF_HOUR
Available inexact recurrence interval recognized by setInexactRepeating(int, long, long, PendingIntent)
when running on Android prior to API 19.
Constant Value: 1800000 (0x00000000001b7740)
INTERVAL_HOUR
long INTERVAL_HOUR
Available inexact recurrence interval recognized by setInexactRepeating(int, long, long, PendingIntent)
when running on Android prior to API 19.
Constant Value: 3600000 (0x000000000036ee80)
RTC
int RTC
Alarm time in System.currentTimeMillis()
(wall clock time in UTC). This alarm does not wake the device up; if it goes off while the device is asleep, it will not be delivered until the next time the device wakes up.
Constant Value: 1 (0x00000001)
RTC_WAKEUP
int RTC_WAKEUP
Alarm time in System.currentTimeMillis()
(wall clock time in UTC), which will wake up the device when it goes off.
Constant Value: 0 (0x00000000)
Public methods
cancel
void cancel (PendingIntent operation)
Remove any alarms with a matching Intent
. Any alarm, of any type, whose Intent matches this one (as defined by filterEquals(Intent)
), will be canceled.
operation
PendingIntent
: IntentSender which matches a previously added IntentSender. This parameter must not be null
. See also:
set(int, long, PendingIntent)
cancel
void cancel (AlarmManager.OnAlarmListener listener)
Remove any alarm scheduled to be delivered to the given AlarmManager.OnAlarmListener
.
listener
AlarmManager.OnAlarmListener
: OnAlarmListener instance that is the target of a currently-set alarm. getNextAlarmClock
AlarmManager.AlarmClockInfo getNextAlarmClock ()
Gets information about the next alarm clock currently scheduled. The alarm clocks considered are those scheduled by any application using the setAlarmClock(AlarmManager.AlarmClockInfo, PendingIntent)
method.
AlarmManager.AlarmClockInfo
An AlarmManager.AlarmClockInfo
object describing the next upcoming alarm clock event that will occur. If there are no alarm clock events currently scheduled, this method will return null
. See also:
setAlarmClock(AlarmManager.AlarmClockInfo, PendingIntent)
AlarmManager.AlarmClockInfo
ACTION_NEXT_ALARM_CLOCK_CHANGED
set
void set (int type, long triggerAtMillis, PendingIntent operation)
Schedule an alarm. Note: for timing operations (ticks, timeouts, etc) it is easier and much more efficient to use Handler
. If there is already an alarm scheduled for the same IntentSender, that previous alarm will first be canceled.
If the stated trigger time is in the past, the alarm will be triggered immediately. If there is already an alarm for this Intent scheduled (with the equality of two intents being defined by filterEquals(Intent)
), then it will be removed and replaced by this one.
The alarm is an Intent broadcast that goes to a broadcast receiver that you registered with registerReceiver(BroadcastReceiver, IntentFilter)
or through the <receiver> tag in an AndroidManifest.xml file.
Alarm intents are delivered with a data extra of type int called Intent.EXTRA_ALARM_COUNT
that indicates how many past alarm events have been accumulated into this intent broadcast. Recurring alarms that have gone undelivered because the phone was asleep may have a count greater than one when delivered.
Note: Beginning in API 19, the trigger time passed to this method is treated as inexact: the alarm will not be delivered before this time, but may be deferred and delivered some time later. The OS will use this policy in order to “batch” alarms together across the entire system, minimizing the number of times the device needs to “wake up” and minimizing battery use. In general, alarms scheduled in the near future will not be deferred as long as alarms scheduled far in the future.
With the new batching policy, delivery ordering guarantees are not as strong as they were previously. If the application sets multiple alarms, it is possible that these alarms’ actual delivery ordering may not match the order of their requested delivery times. If your application has strong ordering requirements there are other APIs that you can use to get the necessary behavior; see setWindow(int, long, long, PendingIntent)
and setExact(int, long, PendingIntent)
.
Applications whose targetSdkVersion
is before API 19 will continue to get the previous alarm behavior: all of their scheduled alarms will be treated as exact.
type
int
: type of alarm.Value is RTC_WAKEUP
, RTC
, ELAPSED_REALTIME_WAKEUP
or ELAPSED_REALTIME
.
triggerAtMillis
long
: time in milliseconds that the alarm should go off, using the appropriate clock (depending on the alarm type). operation
PendingIntent
: Action to perform when the alarm goes off; typically comes from IntentSender.getBroadcast()
. See also:
Handler
setExact(int, long, PendingIntent)
setRepeating(int, long, long, PendingIntent)
setWindow(int, long, long, PendingIntent)
cancel(AlarmManager.OnAlarmListener)
sendBroadcast(Intent)
registerReceiver(BroadcastReceiver, IntentFilter)
filterEquals(Intent)
ELAPSED_REALTIME
ELAPSED_REALTIME_WAKEUP
RTC
RTC_WAKEUP
set
void set (int type, long triggerAtMillis, String tag, AlarmManager.OnAlarmListener listener, Handler targetHandler)
Direct callback version of set(int, long, PendingIntent)
. Rather than supplying a PendingIntent to be sent when the alarm time is reached, this variant supplies an AlarmManager.OnAlarmListener
instance that will be invoked at that time.
The OnAlarmListener’s onAlarm()
method will be invoked via the specified target Handler, or on the application’s main looper if null
is passed as the targetHandler
parameter.
type
int
: type of alarm.Value is RTC_WAKEUP
, RTC
, ELAPSED_REALTIME_WAKEUP
or ELAPSED_REALTIME
.
triggerAtMillis
long
: time in milliseconds that the alarm should go off, using the appropriate clock (depending on the alarm type). tag
String
: string describing the alarm, used for logging and battery-use attribution listener
AlarmManager.OnAlarmListener
: AlarmManager.OnAlarmListener
instance whose onAlarm()
method will be called when the alarm time is reached. A given OnAlarmListener instance can only be the target of a single pending alarm, just as a given PendingIntent can only be used with one alarm at a time. targetHandler
Handler
: Handler
on which to execute the listener’s onAlarm() callback, or null
to run that callback on the main looper. setAlarmClock
void setAlarmClock (AlarmManager.AlarmClockInfo info, PendingIntent operation)
Schedule an alarm that represents an alarm clock. The system may choose to display information about this alarm to the user.
This method is like setExact(int, long, PendingIntent)
, but implies RTC_WAKEUP
.
operation
PendingIntent
: Action to perform when the alarm goes off; typically comes from IntentSender.getBroadcast()
. See also:
set(int, long, PendingIntent)
setRepeating(int, long, long, PendingIntent)
setWindow(int, long, long, PendingIntent)
setExact(int, long, PendingIntent)
cancel(AlarmManager.OnAlarmListener)
getNextAlarmClock()
sendBroadcast(Intent)
registerReceiver(BroadcastReceiver, IntentFilter)
filterEquals(Intent)
setAndAllowWhileIdle
void setAndAllowWhileIdle (int type, long triggerAtMillis, PendingIntent operation)
Like set(int, long, PendingIntent)
, but this alarm will be allowed to execute even when the system is in low-power idle modes. This type of alarm must only be used for situations where it is actually required that the alarm go off while in idle – a reasonable example would be for a calendar notification that should make a sound so the user is aware of it. When the alarm is dispatched, the app will also be added to the system’s temporary whitelist for approximately 10 seconds to allow that application to acquire further wake locks in which to complete its work.
These alarms can significantly impact the power use of the device when idle (and thus cause significant battery blame to the app scheduling them), so they should be used with care. To reduce abuse, there are restrictions on how frequently these alarms will go off for a particular application. Under normal system operation, it will not dispatch these alarms more than about every minute (at which point every such pending alarm is dispatched); when in low-power idle modes this duration may be significantly longer, such as 15 minutes.
Unlike other alarms, the system is free to reschedule this type of alarm to happen out of order with any other alarms, even those from the same app. This will clearly happen when the device is idle (since this alarm can go off while idle, when any other alarms from the app will be held until later), but may also happen even when not idle.
Regardless of the app’s target SDK version, this call always allows batching of the alarm.
type
int
: type of alarm.Value is RTC_WAKEUP
, RTC
, ELAPSED_REALTIME_WAKEUP
or ELAPSED_REALTIME
.
triggerAtMillis
long
: time in milliseconds that the alarm should go off, using the appropriate clock (depending on the alarm type). operation
PendingIntent
: Action to perform when the alarm goes off; typically comes from IntentSender.getBroadcast()
. See also:
set(int, long, PendingIntent)
setExactAndAllowWhileIdle(int, long, PendingIntent)
cancel(AlarmManager.OnAlarmListener)
sendBroadcast(Intent)
registerReceiver(BroadcastReceiver, IntentFilter)
filterEquals(Intent)
ELAPSED_REALTIME
ELAPSED_REALTIME_WAKEUP
RTC
RTC_WAKEUP
setExact
void setExact (int type, long triggerAtMillis, PendingIntent operation)
Schedule an alarm to be delivered precisely at the stated time.
This method is like set(int, long, PendingIntent)
, but does not permit the OS to adjust the delivery time. The alarm will be delivered as nearly as possible to the requested trigger time.
Note: only alarms for which there is a strong demand for exact-time delivery (such as an alarm clock ringing at the requested time) should be scheduled as exact. Applications are strongly discouraged from using exact alarms unnecessarily as they reduce the OS’s ability to minimize battery use.
type
int
: type of alarm.Value is RTC_WAKEUP
, RTC
, ELAPSED_REALTIME_WAKEUP
or ELAPSED_REALTIME
.
triggerAtMillis
long
: time in milliseconds that the alarm should go off, using the appropriate clock (depending on the alarm type). operation
PendingIntent
: Action to perform when the alarm goes off; typically comes from IntentSender.getBroadcast()
. See also:
set(int, long, PendingIntent)
setRepeating(int, long, long, PendingIntent)
setWindow(int, long, long, PendingIntent)
cancel(AlarmManager.OnAlarmListener)
sendBroadcast(Intent)
registerReceiver(BroadcastReceiver, IntentFilter)
filterEquals(Intent)
ELAPSED_REALTIME
ELAPSED_REALTIME_WAKEUP
RTC
RTC_WAKEUP
setExact
void setExact (int type, long triggerAtMillis, String tag, AlarmManager.OnAlarmListener listener, Handler targetHandler)
Direct callback version of setExact(int, long, PendingIntent)
. Rather than supplying a PendingIntent to be sent when the alarm time is reached, this variant supplies an AlarmManager.OnAlarmListener
instance that will be invoked at that time.
The OnAlarmListener’s onAlarm()
method will be invoked via the specified target Handler, or on the application’s main looper if null
is passed as the targetHandler
parameter.
type
int
Value is RTC_WAKEUP
, RTC
, ELAPSED_REALTIME_WAKEUP
or ELAPSED_REALTIME
.
triggerAtMillis
long
tag
String
listener
AlarmManager.OnAlarmListener
targetHandler
Handler
setExactAndAllowWhileIdle
void setExactAndAllowWhileIdle (int type, long triggerAtMillis, PendingIntent operation)
Like setExact(int, long, PendingIntent)
, but this alarm will be allowed to execute even when the system is in low-power idle modes. If you don’t need exact scheduling of the alarm but still need to execute while idle, consider using setAndAllowWhileIdle(int, long, PendingIntent)
. This type of alarm must only be used for situations where it is actually required that the alarm go off while in idle – a reasonable example would be for a calendar notification that should make a sound so the user is aware of it. When the alarm is dispatched, the app will also be added to the system’s temporary whitelist for approximately 10 seconds to allow that application to acquire further wake locks in which to complete its work.
These alarms can significantly impact the power use of the device when idle (and thus cause significant battery blame to the app scheduling them), so they should be used with care. To reduce abuse, there are restrictions on how frequently these alarms will go off for a particular application. Under normal system operation, it will not dispatch these alarms more than about every minute (at which point every such pending alarm is dispatched); when in low-power idle modes this duration may be significantly longer, such as 15 minutes.
Unlike other alarms, the system is free to reschedule this type of alarm to happen out of order with any other alarms, even those from the same app. This will clearly happen when the device is idle (since this alarm can go off while idle, when any other alarms from the app will be held until later), but may also happen even when not idle. Note that the OS will allow itself more flexibility for scheduling these alarms than regular exact alarms, since the application has opted into this behavior. When the device is idle it may take even more liberties with scheduling in order to optimize for battery life.
type
int
: type of alarm.Value is RTC_WAKEUP
, RTC
, ELAPSED_REALTIME_WAKEUP
or ELAPSED_REALTIME
.
triggerAtMillis
long
: time in milliseconds that the alarm should go off, using the appropriate clock (depending on the alarm type). operation
PendingIntent
: Action to perform when the alarm goes off; typically comes from IntentSender.getBroadcast()
. See also:
set(int, long, PendingIntent)
setRepeating(int, long, long, PendingIntent)
setWindow(int, long, long, PendingIntent)
cancel(AlarmManager.OnAlarmListener)
sendBroadcast(Intent)
registerReceiver(BroadcastReceiver, IntentFilter)
filterEquals(Intent)
ELAPSED_REALTIME
ELAPSED_REALTIME_WAKEUP
RTC
RTC_WAKEUP
setInexactRepeating
void setInexactRepeating (int type, long triggerAtMillis, long intervalMillis, PendingIntent operation)
Schedule a repeating alarm that has inexact trigger time requirements; for example, an alarm that repeats every hour, but not necessarily at the top of every hour. These alarms are more power-efficient than the strict recurrences traditionally supplied by setRepeating(int, long, long, PendingIntent)
, since the system can adjust alarms’ delivery times to cause them to fire simultaneously, avoiding waking the device from sleep more than necessary.
Your alarm’s first trigger will not be before the requested time, but it might not occur for almost a full interval after that time. In addition, while the overall period of the repeating alarm will be as requested, the time between any two successive firings of the alarm may vary. If your application demands very low jitter, use one-shot alarms with an appropriate window instead; see setWindow(int, long, long, PendingIntent)
and setExact(int, long, PendingIntent)
.
As of API 19, all repeating alarms are inexact. Because this method has been available since API 3, your application can safely call it and be assured that it will get similar behavior on both current and older versions of Android.
type
int
: type of alarm.Value is RTC_WAKEUP
, RTC
, ELAPSED_REALTIME_WAKEUP
or ELAPSED_REALTIME
.
triggerAtMillis
long
: time in milliseconds that the alarm should first go off, using the appropriate clock (depending on the alarm type). This is inexact: the alarm will not fire before this time, but there may be a delay of almost an entire alarm interval before the first invocation of the alarm. intervalMillis
long
: interval in milliseconds between subsequent repeats of the alarm. Prior to API 19, if this is one of INTERVAL_FIFTEEN_MINUTES, INTERVAL_HALF_HOUR, INTERVAL_HOUR, INTERVAL_HALF_DAY, or INTERVAL_DAY then the alarm will be phase-aligned with other alarms to reduce the number of wakeups. Otherwise, the alarm will be set as though the application had called setRepeating(int, long, long, PendingIntent)
. As of API 19, all repeating alarms will be inexact and subject to batching with other alarms regardless of their stated repeat interval. operation
PendingIntent
: Action to perform when the alarm goes off; typically comes from IntentSender.getBroadcast()
. See also:
Handler
set(int, long, PendingIntent)
cancel(AlarmManager.OnAlarmListener)
sendBroadcast(Intent)
registerReceiver(BroadcastReceiver, IntentFilter)
filterEquals(Intent)
ELAPSED_REALTIME
ELAPSED_REALTIME_WAKEUP
RTC
RTC_WAKEUP
INTERVAL_FIFTEEN_MINUTES
INTERVAL_HALF_HOUR
INTERVAL_HOUR
INTERVAL_HALF_DAY
INTERVAL_DAY
setRepeating
void setRepeating (int type, long triggerAtMillis, long intervalMillis, PendingIntent operation)
Schedule a repeating alarm. Note: for timing operations (ticks, timeouts, etc) it is easier and much more efficient to use Handler
. If there is already an alarm scheduled for the same IntentSender, it will first be canceled.
Like set(int, long, PendingIntent)
, except you can also supply a period at which the alarm will automatically repeat. This alarm continues repeating until explicitly removed with cancel(AlarmManager.OnAlarmListener)
. If the stated trigger time is in the past, the alarm will be triggered immediately, with an alarm count depending on how far in the past the trigger time is relative to the repeat interval.
If an alarm is delayed (by system sleep, for example, for non _WAKEUP alarm types), a skipped repeat will be delivered as soon as possible. After that, future alarms will be delivered according to the original schedule; they do not drift over time. For example, if you have set a recurring alarm for the top of every hour but the phone was asleep from 7:45 until 8:45, an alarm will be sent as soon as the phone awakens, then the next alarm will be sent at 9:00.
If your application wants to allow the delivery times to drift in order to guarantee that at least a certain time interval always elapses between alarms, then the approach to take is to use one-time alarms, scheduling the next one yourself when handling each alarm delivery.
Note: as of API 19, all repeating alarms are inexact. If your application needs precise delivery times then it must use one-time exact alarms, rescheduling each time as described above. Legacy applications whose targetSdkVersion
is earlier than API 19 will continue to have all of their alarms, including repeating alarms, treated as exact.
type
int
: type of alarm.Value is RTC_WAKEUP
, RTC
, ELAPSED_REALTIME_WAKEUP
or ELAPSED_REALTIME
.
triggerAtMillis
long
: time in milliseconds that the alarm should first go off, using the appropriate clock (depending on the alarm type). intervalMillis
long
: interval in milliseconds between subsequent repeats of the alarm. operation
PendingIntent
: Action to perform when the alarm goes off; typically comes from IntentSender.getBroadcast()
. See also:
Handler
set(int, long, PendingIntent)
setExact(int, long, PendingIntent)
setWindow(int, long, long, PendingIntent)
cancel(AlarmManager.OnAlarmListener)
sendBroadcast(Intent)
registerReceiver(BroadcastReceiver, IntentFilter)
filterEquals(Intent)
ELAPSED_REALTIME
ELAPSED_REALTIME_WAKEUP
RTC
RTC_WAKEUP
setTime
void setTime (long millis)
Set the system wall clock time. Requires the permission android.permission.SET_TIME.
millis
long
: time in milliseconds since the Epoch setTimeZone
void setTimeZone (String timeZone)
Sets the system’s persistent default time zone. This is the time zone for all apps, even after a reboot. Use setDefault(TimeZone)
if you just want to change the time zone within your app, and even then prefer to pass an explicit TimeZone
to APIs that require it rather than changing the time zone for all threads.
On android M and above, it is an error to pass in a non-Olson timezone to this function. Note that this is a bad idea on all Android releases because POSIX and the TimeZone
class have opposite interpretations of '+'
and '-'
in the same non-Olson ID.
timeZone
String
: one of the Olson ids from the list returned by getAvailableIDs()
setWindow
void setWindow (int type, long windowStartMillis, long windowLengthMillis, PendingIntent operation)
Schedule an alarm to be delivered within a given window of time. This method is similar to set(int, long, PendingIntent)
, but allows the application to precisely control the degree to which its delivery might be adjusted by the OS. This method allows an application to take advantage of the battery optimizations that arise from delivery batching even when it has modest timeliness requirements for its alarms.
This method can also be used to achieve strict ordering guarantees among multiple alarms by ensuring that the windows requested for each alarm do not intersect.
When precise delivery is not required, applications should use the standard set(int, long, PendingIntent)
method. This will give the OS the most flexibility to minimize wakeups and battery use. For alarms that must be delivered at precisely-specified times with no acceptable variation, applications can use setExact(int, long, PendingIntent)
.
type
int
: type of alarm.Value is RTC_WAKEUP
, RTC
, ELAPSED_REALTIME_WAKEUP
or ELAPSED_REALTIME
.
windowStartMillis
long
: The earliest time, in milliseconds, that the alarm should be delivered, expressed in the appropriate clock’s units (depending on the alarm type). windowLengthMillis
long
: The length of the requested delivery window, in milliseconds. The alarm will be delivered no later than this many milliseconds after windowStartMillis
. Note that this parameter is a duration, not the timestamp of the end of the window. operation
PendingIntent
: Action to perform when the alarm goes off; typically comes from IntentSender.getBroadcast()
. See also:
set(int, long, PendingIntent)
setExact(int, long, PendingIntent)
setRepeating(int, long, long, PendingIntent)
cancel(AlarmManager.OnAlarmListener)
sendBroadcast(Intent)
registerReceiver(BroadcastReceiver, IntentFilter)
filterEquals(Intent)
ELAPSED_REALTIME
ELAPSED_REALTIME_WAKEUP
RTC
RTC_WAKEUP
setWindow
void setWindow (int type, long windowStartMillis, long windowLengthMillis, String tag, AlarmManager.OnAlarmListener listener, Handler targetHandler)
Direct callback version of setWindow(int, long, long, PendingIntent)
. Rather than supplying a PendingIntent to be sent when the alarm time is reached, this variant supplies an AlarmManager.OnAlarmListener
instance that will be invoked at that time.
The OnAlarmListener onAlarm()
method will be invoked via the specified target Handler, or on the application’s main looper if null
is passed as the targetHandler
parameter.
type
int
Value is RTC_WAKEUP
, RTC
, ELAPSED_REALTIME_WAKEUP
or ELAPSED_REALTIME
.
windowStartMillis
long
windowLengthMillis
long
tag
String
listener
AlarmManager.OnAlarmListener
targetHandler
Handler
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