Android Sites
Support
Languages
| java.lang.Object | |
| ↳ | android.app.AlarmManager |
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.
You do not
instantiate this class directly; instead, retrieve it through
Context.getSystemService(Context.ALARM_SERVICE).
| Constants | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 | ||||||||||
| long | INTERVAL_FIFTEEN_MINUTES | Available inexact recurrence intervals recognized by
setInexactRepeating(int, long, long, PendingIntent)
|
|||||||||
| long | INTERVAL_HALF_DAY | ||||||||||
| long | INTERVAL_HALF_HOUR | ||||||||||
| long | INTERVAL_HOUR | ||||||||||
| 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 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Remove any alarms with a matching
Intent. | |||||||||||
Schedule an alarm.
| |||||||||||
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.
| |||||||||||
Schedule a repeating alarm.
| |||||||||||
Set the system wall clock time.
| |||||||||||
Set the system default time zone.
| |||||||||||
|
[Expand]
Inherited Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
From class
java.lang.Object
| |||||||||||
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.
Alarm time in SystemClock.elapsedRealtime() (time since boot, including sleep),
which will wake up the device when it goes off.
Available inexact recurrence intervals recognized by
setInexactRepeating(int, long, long, PendingIntent)
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.
Alarm time in System.currentTimeMillis()
(wall clock time in UTC), which will wake up the device when
it goes off.
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 | IntentSender which matches a previously added IntentSender. |
|---|
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, it will first be canceled.
If the time occurs 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.
| type | One of ELAPSED_REALTIME, ELAPSED_REALTIME_WAKEUP, RTC or RTC_WAKEUP. |
|---|---|
| triggerAtMillis | time in milliseconds that the alarm should go off, using the appropriate clock (depending on the alarm type). |
| operation | Action to perform when the alarm goes off;
typically comes from IntentSender.getBroadcast(). |
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 supplied by setRepeating(int, long, long, PendingIntent), since the
system can adjust alarms' phase 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
setRepeating(int, long, long, PendingIntent) instead.
| type | One of ELAPSED_REALTIME, ELAPSED_REALTIME_WAKEUP}, RTC or RTC_WAKEUP. |
|---|---|
| triggerAtMillis | 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 | interval in milliseconds between subsequent repeats
of the alarm. 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). |
| operation | Action to perform when the alarm goes off;
typically comes from IntentSender.getBroadcast(). |
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 rate at which the alarm will repeat. This alarm continues
repeating until explicitly removed with cancel(PendingIntent). If the time
occurs 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.
| type | One of ELAPSED_REALTIME, ELAPSED_REALTIME_WAKEUP}, RTC or RTC_WAKEUP. |
|---|---|
| triggerAtMillis | time in milliseconds that the alarm should first go off, using the appropriate clock (depending on the alarm type). |
| intervalMillis | interval in milliseconds between subsequent repeats of the alarm. |
| operation | Action to perform when the alarm goes off;
typically comes from IntentSender.getBroadcast(). |
Set the system wall clock time. Requires the permission android.permission.SET_TIME.
| millis | time in milliseconds since the Epoch |
|---|
Set the system default time zone. Requires the permission android.permission.SET_TIME_ZONE.
| timeZone | in the format understood by TimeZone
|
|---|