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How to cancel a scheduled local notification in Kotlin?

I have an app where the user creates its own local notifications. User declares name, date and time the nofication should popup and specifies the repeating frequency.
Then the notifications are listed in a recyclerview in another fragment.
The user is able to delete notification by swiping its recyclerview item to the left.
But when I create a notification, delete it then it still pops up at the specified time.
I am storing the notificationID in SharedPreferences as a date when its created (so that I can store it in my DB). I am passing it as a string with putExtra to my BroadcastReceiver class, I am getting the notificationID as a String in my BroadcastReceiver class with getStringExtra. Then passing the same notificationID.toInt() to my pendingIntent.getActivity. Then in my Fragment with recyclerView I am passing the same notificationID for cancelling and it still doesn't cancel.
Perhaps I'm using wrong flags?
Thanks a lot for any help.
Here's my BroadcastReceiver class:
const val titleExtra = "titleExtra"
const val descriptionExtra = "descriptionExtra"
val notificationID = "notificationID"
class Notification: BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
val intentToRepeat = Intent(context, MainActivity::class.java)
val id = intent.getStringExtra(notificationID).toString()
val pendingIntent = PendingIntent.getActivity(context, id.toInt(), intentToRepeat, PendingIntent.FLAG_UPDATE_CURRENT or PendingIntent.FLAG_IMMUTABLE)
val notification = NotificationCompat.Builder(context, channelID)
.setSmallIcon(R.drawable.ic_launcher_foreground)
.setContentTitle(intent.getStringExtra(titleExtra))
.setContentText(intent.getStringExtra(descriptionExtra))
.setContentIntent(pendingIntent)
.setAutoCancel(true)
.build()
val manager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
if (intent.action == "cancel") {
manager.cancel(id.toInt())
}
else {
manager.notify(id.toInt(), notification)
}
}
}
My AndroidManifest:
<receiver android:name=".powiadomienia.Powiadomienie" android:enabled="true"
android:exported="false">
<intent-filter>
<action android:name="cancel"/>
<action android:name="create" />
</intent-filter>
</receiver>
In my recyclerview with notifications listed:
val currentNotification: SetNotification = listAdapter.getNotificationByPosition(viewHolder.bindingAdapterPosition)
if(direction == ItemTouchHelper.LEFT) {
// CANCEL
//val manager = requireContext().getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
//manager.cancel(currentPowiadomienie.notificationId!!)
val alarmManager = requireActivity().getSystemService(Context.ALARM_SERVICE) as AlarmManager
val intent = Intent(requireContext(), Notification::class.java)
intent.action = "cancel"
val pendingIntent = PendingIntent.getService(requireContext(), currentNotification.notificationId!!.toInt(), intent, PendingIntent.FLAG_CANCEL_CURRENT or PendingIntent.FLAG_IMMUTABLE)
pendingIntent?.let { _pendingIntent ->
alarmManager.cancel(_pendingIntent)
}
Neither manager.cancel() nor alarmManager.cancel() works.
The notification creates but how to cancel it?!

I think you need to call notifydatasetchanged() method after the alarmManager.cancel() like this:
val currentNotification: SetNotification =
listAdapter.getNotificationByPosition(viewHolder.bindingAdapterPosition)
if(direction == ItemTouchHelper.LEFT) {
val alarmManager =
requireActivity().getSystemService(Context.ALARM_SERVICE) as AlarmManager
val intent = Intent(requireContext(), Notification::class.java)
intent.action = "cancel"
val pendingIntent = PendingIntent.getService(requireContext(),
currentNotification.notificationId!!.toInt(), intent,
PendingIntent.FLAG_CANCEL_CURRENT or
PendingIntent.FLAG_IMMUTABLE)
pendingIntent?.let { _pendingIntent ->
alarmManager.cancel(_pendingIntent)
notifyDataSetChanged()
}

I've solved my issue for not canceling coming notifications:
I think I was passing the wrong context. Check if you're passing the right one
To cancel a notification:
private fun removeAlarm(id: Int){
val alarmManager = activity?.getSystemService(Context.ALARM_SERVICE) as AlarmManager
// Notification = BroadcastReceiver class
val intent = Intent(requireContext(), Notification::class.java)
val pendingIntent = PendingIntent.getBroadcast(requireContext(), id, intent, PendingIntent.FLAG_IMMUTABLE)
alarmManager.cancel(pendingIntent)
}

AlarmManager with Notification in Android does not show any notifications

I try to create daily notification for my application. In order to test the application I set the interval for the notifications to 15 minutes. Unfortunately, no notification is shown. Neither when the application is running nor when it is closed. I tried to inspire myself with these solutions:
https://stackoverflow.com/questions/33055129/how-to-show-a-notification-everyday-at-a-certain-time-even-when-the-app-is-close
https://developer.android.com/codelabs/android-training-alarm-manager#0
https://github.com/google-developer-training/android-fundamentals-apps-v2/tree/master/StandUp (repository for the previous link)
I added uses-permissions and receiver to the manifest file.
manifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.ovu">
<uses-permission android:name = "android.permission.VIBRATE" />
<uses-permission android:name="com.android.alarm.permission.SET_ALARM"/>
<!-- Permission to start Alarm on device reboot -->
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:roundIcon="#mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity
...
</activity>
<receiver android:name= ".DailyNotificationReceiver">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED"/>
</intent-filter>
</receiver>
</application>
</manifest>
This class extends BroadcastReceiver class and overrides onReceive method.
DailyNotificationReceiver
class DailyNotificationReceiver : BroadcastReceiver() {
companion object {
// Notification ID.
private const val NOTIFICATION_ID = 0
// Notification channel ID.
private const val PRIMARY_CHANNEL_ID = "primary_notification_channel"
}
private lateinit var mNotificationManager: NotificationManager
private val notificationContent = "Please measure your temperature and cervical mucus"
private val contentTitle = "Provide me your temperature and cervical mucus!"
override fun onReceive(context: Context, intent: Intent) {
mNotificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
// Deliver the notification.
deliverNotification(context);
}
private fun deliverNotification(context: Context) {
val contentIntent = Intent(context, MainActivity::class.java)
val contentPendingIntent = PendingIntent.getActivity(context, NOTIFICATION_ID, contentIntent, PendingIntent.FLAG_UPDATE_CURRENT)
// Build the notification
val builder = NotificationCompat.Builder(context, PRIMARY_CHANNEL_ID)
.setSmallIcon(R.drawable.ic_dialog_alert)
.setContentTitle(contentTitle)
.setContentText(notificationContent)
.setContentIntent(contentPendingIntent)
.setPriority(NotificationCompat.PRIORITY_HIGH)
.setAutoCancel(true)
.setDefaults(NotificationCompat.DEFAULT_ALL)
// Deliver the notification
mNotificationManager.notify(NOTIFICATION_ID, builder.build())
}
}
In this activity, instance of AlarmManager should set daily repeating.
ActivityNotification
class ActivityNotification : AppCompatActivity() {
companion object {
// Notification ID.
private const val NOTIFICATION_ID = 0
// Notification channel ID.
private const val PRIMARY_CHANNEL_ID = "primary_notification_channel"
}
private lateinit var mNotificationManager: NotificationManager
private fun notifyUser(){
val notifyIntent = Intent(this, DailyNotificationReceiver::class.java)
val notifyPendingIntent = PendingIntent.getBroadcast(this, NOTIFICATION_ID, notifyIntent,
PendingIntent.FLAG_UPDATE_CURRENT)
val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
val repeatInterval = AlarmManager.INTERVAL_FIFTEEN_MINUTES
val triggerTime = (SystemClock.elapsedRealtime()
+ repeatInterval)
alarmManager.setInexactRepeating(AlarmManager.ELAPSED_REALTIME_WAKEUP,
triggerTime, repeatInterval,
notifyPendingIntent)
// Create the notification channel.
createNotificationChannel();
Toast.makeText(this, "Alarm's set", Toast.LENGTH_LONG).show()
}
private fun createNotificationChannel() {
// Create a notification manager object.
mNotificationManager = getSystemService(NOTIFICATION_SERVICE) as NotificationManager
// Notification channels are only available in OREO and higher.
// So, add a check on SDK version.
if (Build.VERSION.SDK_INT >=
Build.VERSION_CODES.O) {
// Create the NotificationChannel with all the parameters.
val notificationChannel = NotificationChannel(PRIMARY_CHANNEL_ID,
"Stand up notification",
NotificationManager.IMPORTANCE_HIGH)
notificationChannel.enableLights(true)
notificationChannel.lightColor = Color.RED
notificationChannel.enableVibration(true)
notificationChannel.description = "Notifies every 15 minutes to " +
"stand up and walk"
mNotificationManager.createNotificationChannel(notificationChannel)
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_notification)
editTextNotificationHour = findViewById(R.id.editTextChangedNotification)
mNotificationManager = getSystemService(NOTIFICATION_SERVICE) as NotificationManager
}
fun changeNotificationHour(view: View){
notifyUser()
val intent = Intent(this, ProfileActivity::class.java)
startActivity(intent)
finish()
}
I'd be really happy if you guys can help me to find the solution.

Firstly, let's start by enabling our BroadcastReceiver in Manifest by changing our code to this:
<receiver
android:name= ".DailyNotificationReceiver"
android:enabled="true"
android:exported="true">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED"/>
</intent-filter>
</receiver>
Secondly, I am a bit unsure of the purpose of the ActivityNotification Activity.
It would be more than enough to create a simple class like Alarms.
From there you can define all the methods you need to set up an alarm. Something like this:
class InternetDaysLeftAlarm #Inject constructor(
#ApplicationContext val context: Context
) {
/**
* Function is used to schedule one-time Alarm that will trigger on specific time.
*
* #param hourOfDay -> parameter defines what o'clock should the alarm be triggered at. (24-hour)
* default value is:
* #see INTERNET_DAYS_LEFT_ALARM_DEFAULT_TRIGGER_HOUR
*/
fun scheduleAlarm(hourOfDay: Int = INTERNET_DAYS_LEFT_ALARM_DEFAULT_TRIGGER_HOUR) {
val alarmManager = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
val intent = Intent(context, InternetDaysLeftReceiver::class.java)
intent.action = INTENT_ACTION_INTERNET_DAYS_LEFT_ALARM
val pendingIntent = PendingIntent.getBroadcast(context, 0, intent, 0)
val msUntilTriggerHour: Long = TimeUnit.MINUTES.toMillis(minutesUntilOClock(hourOfDay))
// Calculating and adding jitter in order to ease load on server
val jitter: Long = TimeUnit.MINUTES.toMillis(Random.nextInt(0, 420).toLong())
val alarmTimeAtUTC: Long = System.currentTimeMillis() + msUntilTriggerHour + jitter
// Enabling BootReceiver
val bootReceiver = ComponentName(context, BootReceiver::class.java)
context.packageManager.setComponentEnabledSetting(
bootReceiver,
PackageManager.COMPONENT_ENABLED_STATE_ENABLED,
PackageManager.DONT_KILL_APP
)
/**
* Schedules the Alarm based on Android Version.
*
* As per AlarmManager documentation to guarantee Alarm execution at specified time we use following methods:
*
* #see AlarmManager.setExactAndAllowWhileIdle -> Android.M [API 23] and above.
* #see AlarmManager.setAlarmClock -> Everything below Android M.
*/
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) {
alarmManager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, alarmTimeAtUTC, pendingIntent)
} else {
alarmManager.setAlarmClock(AlarmManager.AlarmClockInfo(alarmTimeAtUTC, pendingIntent), pendingIntent)
}
}
Notifications can be handle by:
Creating a separate Notifications class
or
Handling all the notification things like creating channel and sending them inside BroadcastReceiver when you receive an Alarm.

Android Forground sevice stops when the app is closed

I am starting a background service which receives data in the background, so for this, I have used android foreground service, the service works perfectly in some mobiles (MI A2 Stock Android), but in some mobiles when I remove the application from background tray the service gets destroyed.
class MyService : Service() {
private val CHANNEL_ID = "ForegroundService"
companion object {
fun stopService(context: Context) {
val stopIntent = Intent(context, MyService::class.java)
context.stopService(stopIntent)
}
}
override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
// I get some data from intent
// My code which runs in the background
createNotificationChannel()
val notificationIntent = Intent(this, MainActivity::class.java)
val pendingIntent = PendingIntent.getActivity(
this,
0, notificationIntent, 0
)
val notification = NotificationCompat.Builder(this, CHANNEL_ID)
.setContentTitle("App is syncing")
.setContentText("")
.setPriority(2)
.setSmallIcon(android.R.drawable.ic_dialog_alert)
.setContentIntent(pendingIntent)
.build()
startForeground(190, notification)
return START_NOT_STICKY
}
override fun onBind(intent: Intent): IBinder? {
return null
}
private fun createNotificationChannel() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val serviceChannel = NotificationChannel(
CHANNEL_ID, "Foreground Service Channel",
NotificationManager.IMPORTANCE_DEFAULT
)
val manager = getSystemService(NotificationManager::class.java)
manager!!.createNotificationChannel(serviceChannel)
}
}
}
This how I start the service
val serviceIntent = Intent(this, MyService::class.java)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
startForegroundService(serviceIntent)
} else {
startService(serviceIntent)
}
So my question is how can I make my service running even when the APP is removed from the background tray.

Do these things
1) Restart the service when app is closed by overriding this method in
your service class , copy and paste this
override fun onTaskRemoved(rootIntent: Intent?) {
val restartServiceIntent = Intent(applicationContext, this.javaClass)
restartServiceIntent.setPackage(packageName)
val restartServicePendingIntent = PendingIntent.getService(
applicationContext,
1,
restartServiceIntent,
PendingIntent.FLAG_ONE_SHOT
)
val alarmService =
applicationContext.getSystemService(Context.ALARM_SERVICE) as AlarmManager
alarmService[AlarmManager.ELAPSED_REALTIME, SystemClock.elapsedRealtime() + 1000] =
restartServicePendingIntent
super.onTaskRemoved(rootIntent)
}
2) Change this START_NOT_STICKY to START_STICKY
3) Ask user to enable autorun permission from settings , this feature
is provided in custom os like mini devices, vivo,huawei and oppo etc.
4) and you forgot to restart the service on device boot up like you
need to use a broadcast receiver to restart service when the device
restarts

Android - AlarmManager not firing BroadcastReceiver to show Local Notifications

I am writing a prayer application which requires the application to show Local Notifications on PrayerTimes. Prayer times and different for each day, thus I am using the following bit of code to show a Location Notification from BroadcastReceiver and right after that schedule next notification.
The problem is, the application is required to open at least once a day for the notifications to keep firing on their specific timings.
Is there a way to schedule BroadcastReceiver using Alarm Manager to fire Local Notifications without opening the app?
fun MakkahPrayer.setNotificationForPrayer(prayer: Prayer, date: Date) {
val app = App.instance!!.applicationContext
val preferences = PreferenceManager.getInstance(app)
if(!preferences.isPrayerAlarmSet(prayer.name)) {
val calendar = Calendar.getInstance()
calendar.add(Calendar.DAY_OF_YEAR, 0)
val dayOfYear = calendar[Calendar.DAY_OF_YEAR]
NotificationUtils.instance.setNotification(date.time, prayer.name, dayOfYear.toString())
preferences.setPrayerIsAlarmOn(prayer.name, true)
}
}
NotificationUtils.kt
class NotificationUtils {
companion object {
val instance = NotificationUtils()
}
fun setNotification(timeInMilliSeconds: Long, name: String, day: String) {
val cal = Calendar.getInstance()
cal.time = Date()
val millis = cal.timeInMillis
if (timeInMilliSeconds > 0 && timeInMilliSeconds > millis) {
val key = name + day
val alarmManager =
App.instance?.getSystemService(Activity.ALARM_SERVICE) as AlarmManager
val alarmIntent = Intent(App.instance?.applicationContext, AlarmReceiver::class.java)
alarmIntent.putExtra("prayer", name)
alarmIntent.putExtra("timestamp", timeInMilliSeconds)
alarmIntent.putExtra("notificationID", key)
val calendar = Calendar.getInstance()
calendar.timeInMillis = timeInMilliSeconds
val pendingIntent = PendingIntent.getBroadcast(
App.instance,
timeInMilliSeconds.toInt(),
alarmIntent,
PendingIntent.FLAG_UPDATE_CURRENT
)
alarmManager.setExact(AlarmManager.RTC_WAKEUP, timeInMilliSeconds, pendingIntent)
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
alarmManager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, timeInMilliSeconds, pendingIntent)
} else {
alarmManager.setExact(AlarmManager.RTC_WAKEUP, timeInMilliSeconds, pendingIntent)
}
}
}
}
AlarmReceiver.kt
class AlarmReceiver : BroadcastReceiver() {
companion object {
private lateinit var mNotification: Notification
const val CHANNEL_ID = "CHANNEL_ID"
const val CHANNEL_NAME = "Prayer Notification"
}
override fun onReceive(context: Context, intent: Intent) {
val manager = createChannel(context)
showNotification(context, intent, manager)
setNextPrayerAlarm(intent)
}
private fun setNextPrayerAlarm(intent: Intent) {
if (intent.extras != null) {
val prayerName = intent.extras!!.getString("prayer", "Prayer")
val prayer = Prayer.valueOf(prayerName)
MakkahPrayer.instance.removePrayerNotification(prayer)
}
val (nextPrayer, date) = MakkahPrayer.instance.nextPrayerWithTime()
MakkahPrayer.instance.setNotificationForPrayer(nextPrayer, date)
}
private fun showNotification(
context: Context,
intent: Intent,
notificationManager: NotificationManager
) {
var timestamp: Long = 0
var prayerName = "Prayer"
var mNotificationId = ""
if (intent.extras != null) {
timestamp = intent.extras!!.getLong("timestamp")
prayerName = intent.extras!!.getString("prayer", "Prayer")
mNotificationId = intent.extras!!.getString("notificationID", "")
}
if (timestamp > 0) {
val notifyIntent = Intent(context, MainActivity::class.java)
val title = capitalize(prayerName)
val message = "It is $title time"
notifyIntent.flags = Intent.FLAG_ACTIVITY_NEW_TASK
val calendar = Calendar.getInstance()
calendar.timeInMillis = timestamp
val pendingIntent = PendingIntent.getActivity(
context,
0,
notifyIntent,
PendingIntent.FLAG_UPDATE_CURRENT
)
val uri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION)
mNotification = NotificationCompat.Builder(context, NotificationService.CHANNEL_ID)
.setContentIntent(pendingIntent)
.setSmallIcon(R.drawable.ic_alarm_black_24dp)
.setLargeIcon(
BitmapFactory.decodeResource(
context.resources,
R.mipmap.ic_launcher
)
)
.setSound(uri)
.setAutoCancel(true)
.setContentTitle(title)
.setStyle(
NotificationCompat.BigTextStyle()
.bigText(message)
)
.setColor(ContextCompat.getColor(context, R.color.colorSecondary))
.setContentText(message).build()
notificationManager.notify(timestamp.toInt(), mNotification)
}
}
#SuppressLint("NewApi")
private fun createChannel(context: Context): NotificationManager {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val soundUri =
Uri.parse(ContentResolver.SCHEME_ANDROID_RESOURCE + "://" + App.instance?.applicationContext?.packageName + "/" + R.raw.azan)
val audioAttributes = AudioAttributes.Builder()
.setContentType(AudioAttributes.CONTENT_TYPE_SONIFICATION)
.setUsage(AudioAttributes.USAGE_NOTIFICATION)
.build()
val notificationManager =
context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
val importance = NotificationManager.IMPORTANCE_HIGH
val channel = NotificationChannel(CHANNEL_ID, CHANNEL_NAME, importance)
channel.enableVibration(true)
channel.setShowBadge(true)
channel.canShowBadge()
channel.enableLights(true)
channel.lightColor = context.getColor(R.color.colorSecondary)
channel.description =
context.getString(R.string.notification_channel_description)
channel.setSound(soundUri, audioAttributes)
channel.lockscreenVisibility = Notification.VISIBILITY_PUBLIC
notificationManager.createNotificationChannel(channel)
return notificationManager
} else {
return context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
}
}
}
Edit:
After using the following methods, as described by people below, it still is not working, i.e app must be open at least one time in 24 hours, for it to produce local notifications.
I am looking for a solution, where the app should not have to be open for leats say 4,5 days and the app should deliver local notifications.
For now, it works for only 24 hours, when the next day comes, notifications stop firing, requiring the app to be open for at least once a day.

You can create a PrayerWorker using Androidx Work Manager to schedule a background API/setting of notifications (all without using opening app, and instead being trigered when notification is received.
Documentation can be found here
Your setNextPrayerAlarm function will instead have the logic moved to the PrayerWorker and look something like this :
private fun setNextPrayerAlarm(intent: Intent) {
if (intent.extras != null) {
val oneTimeWorkRequestBuilder = OneTimeWorkRequest.Builder(PrayerWorker::class.java)
oneTimeWorkRequestBuilder.setInputData(`put your input data here`)
WorkManager.getInstance(context).enqueueUniqueWork("setPrayerWorker",ExistingWorkPolicy.REPLACE, oneTimeWorkRequestBuilder.build())
}
}
and the PrayerWorker may look something like this
class PrayerWorker(context: Context, workerParameters: WorkerParameters): Worker(context, workerParameters) {
override fun doWork(): Result {
//Insert logic to determine alarms to set
return Result.success() //for success case
}
}
EDIT 1 :
Hi, i should have been clearer in the method, sorry. There's two ways you can make this a repeating alarm.
Method 1:
Modify the OneTimeWorkRequest to a PeriodicWorkRequest(refer to documentation here). Using this method, you can specify how you want the worker that sets to repeat (e.g. every 2 hours, every 24 hours). The min interval is 15 mins.
Method 2:
Modify PrayerWorker to also schedule the next worker. This will utilise the fact that you can add a delay to the triggering of the worker(refer to documentation), which in this case will be 24 hours. Below is the example
class PrayerWorker(context: Context, workerParameters: WorkerParameters): Worker(context, workerParameters) {
override fun doWork(): Result {
//Insert logic to determine alarms to set
val oneTimeWorkRequestBuilder = OneTimeWorkRequest.Builder(PrayerWorker::class.java)
oneTimeWorkRequestBuilder.setInputData(`put your input data here`)
oneTimeWorkRequestBuilder.setInitialDelay(`initialDelay`, `timeUnit`)
WorkManager.getInstance(context).enqueueUniqueWork("setPrayerWorker",ExistingWorkPolicy.REPLACE, oneTimeWorkRequestBuilder.build())
return Result.success() //for success case
}
}

Try following steps
1. In NotificationUtils.kt add an intent Flag FLAG_RECEIVER_FOREGROUND
as like below which will do the trick for you
val alarmIntent = Intent(App.instance?.applicationContext, AlarmReceiver::class.java)
alarmIntent.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
alarmIntent.putExtra("prayer", name)
....
...
2. Also make sure you have registered AlarmReceiver in Manifest
like below
<receiver android:name="com.myapp.receiver.AlarmReceiver">
</receiver>

I don't know which android Sdk level your app is targeting, but Google has changed it's APIs starting from O. Declaring implicit Broadcast receiver from manifest will not work.
As part of the Android 8.0 (API level 26) Background Execution Limits, apps that target the API level 26 or higher can no longer register broadcast receivers for implicit broadcasts in their manifest. However, several broadcasts are currently exempted from these limitations. Apps can continue to register listeners for the following broadcasts, no matter what API level the apps target.
more on that here: https://developer.android.com/guide/components/broadcast-exceptions

How to set an alarm on Android Q?

Background
Android Q seems to have plenty of new restrictions, but alarms shouldn't be one of them:
https://developer.android.com/guide/components/activities/background-starts
The problem
It seems that old code that I made for setting an alarm, which worked fine on P, can't work well anymore:
MainActivity.kt
class MainActivity : AppCompatActivity() {
private lateinit var manager: AlarmManager
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
manager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
button.setOnClickListener {
Log.d("AppLog", "alarm set")
Toast.makeText(this, "alarm set", Toast.LENGTH_SHORT).show()
val timeToTrigger = System.currentTimeMillis() + 10 * 1000
setAlarm(this, timeToTrigger, 1)
}
}
companion object {
fun setAlarm(context: Context, timeToTrigger: Long, requestId: Int) {
val manager = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
val pendingIntent = PendingIntent.getBroadcast(context, requestId, Intent(context, AlarmReceiver::class.java), PendingIntent.FLAG_UPDATE_CURRENT)
when {
VERSION.SDK_INT >= VERSION_CODES.LOLLIPOP -> manager.setAlarmClock(AlarmClockInfo(timeToTrigger, pendingIntent), pendingIntent)
VERSION.SDK_INT >= VERSION_CODES.KITKAT -> manager.setExact(AlarmManager.RTC_WAKEUP, timeToTrigger, pendingIntent)
else -> manager.set(AlarmManager.RTC_WAKEUP, timeToTrigger, pendingIntent)
}
}
}
}
The receiver does get the Intent, but when it tries to open the Activity, sometimes nothing occurs:
AlarmReceiver.kt
class AlarmReceiver : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
Log.d("AppLog", "AlarmReceiver onReceive")
context.startActivity(Intent(context, Main2Activity::class.java).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK))
}
}
Seeing this as a bug, I reported here (including sample code)
What I've tried
I tried to find what's new on Q, to see what could cause it, and I couldn't find it.
I also tried (if you look at the code) to directly open the Activity instead of via a BroadcastReceiver.
And, I tried to set the BroadcastReceiver to run on a different process.
All of those didn't help.
What I have found is that while some alarm clock apps fail to work properly (such as Timely), some apps work just fine (such as "Alarm Clock Xtreme").
The questions
On Android Q, is there an official way to let alarms work correctly? To open an Activity that will be shown to the user, exactly as an alarm clock app should?
What's wrong in the code I've made? How come it works on P but not always on Q?
EDIT: OK after being adviced to have a notification shown while I start the Activity, and also use FullScreenIntent, I got something to work, but it's only working when the screen is turned off. When the screen is turned on, it only shows the notification, which is a bad thing because the whole point is to have an alarm being shown to the user, and some users (like me) don't want to have heads-up-notification for alarms, popping out in the middle of something and not pausing anything. I hope someone can help with this, as this used to be a very easy thing to do, and now it got way too complex...
Here's the current code (available here) :
NotificationId
object NotificationId {
const val ALARM_TRIGGERED = 1
#JvmStatic
private var hasInitialized = false
#UiThread
#JvmStatic
fun initNotificationsChannels(context: Context) {
if (hasInitialized || Build.VERSION.SDK_INT < Build.VERSION_CODES.O)
return
hasInitialized = true
val channelsToUpdateOrAdd = HashMap<String, NotificationChannel>()
val channel = NotificationChannel(context.getString(R.string.channel_id__alarm_triggered), context.getString(R.string.channel_name__alarm_triggered), NotificationManager.IMPORTANCE_HIGH)
channel.description = context.getString(R.string.channel_description__alarm_triggered)
channel.enableLights(true)
channel.setSound(null, null)
channel.lockscreenVisibility = Notification.VISIBILITY_PUBLIC
channel.enableVibration(false)
channel.setShowBadge(false)
channelsToUpdateOrAdd[channel.id] = channel
//
val notificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
val existingChannels = notificationManager.notificationChannels
if (existingChannels != null)
for (existingChannel in existingChannels) {
// The importance of an existing channel will only be changed if the new importance is lower than the current value and the user has not altered any settings on this channel.
// The group an existing channel will only be changed if the channel does not already belong to a group. All other fields are ignored for channels that already exist.
val channelToUpdateOrAdd = channelsToUpdateOrAdd[existingChannel.id]
if (channelToUpdateOrAdd == null) //|| channelToUpdateOrAdd.importance > existingChannel.importance || (existingChannel.group != null && channelToUpdateOrAdd.group != existingChannel.group))
notificationManager.deleteNotificationChannel(existingChannel.id)
}
for (notificationChannel in channelsToUpdateOrAdd.values) {
notificationManager.createNotificationChannel(notificationChannel)
}
}
}
MyService.kt
class MyService : Service() {
override fun onBind(p0: Intent?): IBinder? = null
override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
Log.d("AppLog", "MyService onStartCommand")
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
NotificationId.initNotificationsChannels(this)
val builder = NotificationCompat.Builder(this, getString(R.string.channel_id__alarm_triggered)).setSmallIcon(android.R.drawable.sym_def_app_icon) //
.setPriority(NotificationCompat.PRIORITY_HIGH).setCategory(NotificationCompat.CATEGORY_ALARM)
builder.setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
builder.setShowWhen(false)
builder.setContentText("Alarm is triggered!")
builder.setContentTitle("Alarm!!!")
val fullScreenIntent = Intent(this, Main2Activity::class.java)
val fullScreenPendingIntent = PendingIntent.getActivity(this, 0,
fullScreenIntent, PendingIntent.FLAG_UPDATE_CURRENT)
builder.setFullScreenIntent(fullScreenPendingIntent, true)
startForeground(NotificationId.ALARM_TRIGGERED, builder.build())
startActivity(Intent(this, Main2Activity::class.java).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK))
Handler().postDelayed({
stopForeground(true)
stopSelf()
}, 2000L)
} else {
startActivity(Intent(this, Main2Activity::class.java).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK))
}
return super.onStartCommand(intent, flags, startId)
}
}
MainActivity.kt
class MainActivity : AppCompatActivity() {
private lateinit var manager: AlarmManager
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
manager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
button.setOnClickListener {
Log.d("AppLog", "alarm set")
Toast.makeText(this, "alarm set", Toast.LENGTH_SHORT).show()
val timeToTrigger = System.currentTimeMillis() + 10 * 1000
setAlarm(this, timeToTrigger, 1)
}
}
companion object {
fun setAlarm(context: Context, timeToTrigger: Long, requestId: Int) {
val manager = context.getSystemService(Context.ALARM_SERVICE) as AlarmManager
val pendingIntent = PendingIntent.getBroadcast(context, requestId, Intent(context, AlarmReceiver::class.java), PendingIntent.FLAG_UPDATE_CURRENT)
// val pendingIntent = PendingIntent.getBroadcast(context, requestId, Intent(context, Main2Activity::class.java), PendingIntent.FLAG_UPDATE_CURRENT)
// val pendingIntent = PendingIntent.getService(context, requestId, Intent(context, MyService::class.java), PendingIntent.FLAG_UPDATE_CURRENT)
when {
VERSION.SDK_INT >= VERSION_CODES.LOLLIPOP -> manager.setAlarmClock(AlarmClockInfo(timeToTrigger, pendingIntent), pendingIntent)
VERSION.SDK_INT >= VERSION_CODES.KITKAT -> manager.setExact(AlarmManager.RTC_WAKEUP, timeToTrigger, pendingIntent)
else -> manager.set(AlarmManager.RTC_WAKEUP, timeToTrigger, pendingIntent)
}
}
}
}
AlarmReceiver.kt
class AlarmReceiver : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent) {
Log.d("AppLog", "AlarmReceiver onReceive")
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
context.startForegroundService(Intent(context, MyService::class.java))
} else context.startService(Intent(context, MyService::class.java))
}
}

What's wrong in the code I've made? How come it works on P but not always on Q?
You are attempting to start an activity from the background. That is banned on Android 10+ for the most part.
According to the docs, alarms shouldn't be harmed.
From the material that you quoted, with emphasis added: "The app receives a notification PendingIntent from the system". You are not using notifications. And, therefore, this exception does not apply.
On Android Q, is there an official way to let alarms work correctly? To open an Activity that will be shown to the user, exactly as an alarm clock app should?
Use a notification with a full-screen Intent, as is covered in the documentation. If the screen is locked, your activity will be displayed when the notification is raised. If the screen is unlocked, a high-priority ("heads up") notification will be displayed instead. In other words:
If the device is not being used, you get what you want
If the device is probably being used, the user find out about the event without your taking over the screen, so you do not interfere with whatever the user is doing (e.g., relying on a navigation app while driving)