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Notification channel not found, Image view not changing, do receivers work?

I have 3 parts of code that are not working on my application, here they are:
Main activity -
class MainActivity : AppCompatActivity() {
var CHANNEL_ID = "myChannel"
private var mAlarmManager : AlarmManager? = null
private fun createNotificationChannel() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val name = getString(R.string.channel_name)
val descriptionText = getString(R.string.channel_description)
val importance = NotificationManager.IMPORTANCE_DEFAULT
val channel = NotificationChannel(CHANNEL_ID, name, importance).apply {
description = descriptionText
}
val notificationManager: NotificationManager =
getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager.createNotificationChannel(channel)
}
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val mIntent = Intent(this, MyReceiver::class.java)
val mPendingIntent = PendingIntent.getBroadcast(this, 0, mIntent, PendingIntent.FLAG_UPDATE_CURRENT)
val mAlarmManager = this
.getSystemService(Context.ALARM_SERVICE) as AlarmManager
mAlarmManager.setRepeating(
AlarmManager.RTC_WAKEUP, System.currentTimeMillis(),
60000, mPendingIntent
)
Qinperation -
class Qinperation : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.qinsperational)
val back18 = findViewById<Button>(R.id.back18)
back18.setOnClickListener {
val intent = Intent(this, MainActivity::class.java)
startActivity(intent)
}
}
And MyReceiver -
class MyReceiver : BroadcastReceiver() {
var CHANNEL_ID = "myChannel"
override fun onReceive(context: Context, intent: Intent) {
Toast.makeText(context,"This toast will be shown every X minutes", Toast.LENGTH_LONG).show()
Log.i("TAG","/////////////////// SHOW NOTIFICATION NOW //////////////////////")
val builder = NotificationCompat.Builder(context, CHANNEL_ID)
.setSmallIcon(R.drawable.orange)
.setLargeIcon(BitmapFactory.decodeResource(context.resources,R.mipmap.ic_launcher_round))
.setContentTitle("My notification")
.setContentText("Much longer text that cannot fit one line...")
.setStyle(
NotificationCompat.BigTextStyle()
.bigText("Much longer text that cannot fit one line...Much longer text that cannot fit one line..."))
.setPriority(NotificationCompat.PRIORITY_DEFAULT)
with(NotificationManagerCompat.from(context)) {
notify(12345, builder.build()) }
if (context !is Qinperation) return
val imageView = context.findViewById<View>(R.id.paininass) as ImageView
val quotes = arrayOf(R.drawable.i1, R.drawable.i2, R.drawable.i3, R.drawable.i5, R.drawable.i6, R.drawable.i7, R.drawable.i8, R.drawable.i9, R.drawable.i10, R.drawable.i11, R.drawable.i12)
val quote = quotes.random()
imageView.setImageResource(quote)
}
}
I want the receiver to run every set period (at the moment every minute), and then a notification to pop up and the image in the Qinperation activity to change to a randomized one. I know the receiver works due to the toast popping up successfully every minute. It then continues to say a notification cannot be posted to the notification channel "myChannel". After some research I concluded I needed to set up a channel that I thought I did in the main activity (using the android documentation), but it still doesn't work. It runs and just has that message pop up at the bottom. How would I successfully create this channel and run it so a notification pops up every set period of time?
As for the image view, I have the randomizer set up to run in the receiver and then based of the random image the image view to be set. It however stays blank throughout. Am I using the right command?
All help or tips are appreciated :)

Repeating notifications issue

I'm struggling with notifications.
I want to randomly select text to display in the notification (using random() method on the array of String objects from separate object file NotificationData where I only had one immutable variable called notificationData), which should appear once a day at a specific time (but for now, for the purpose of the test, I wrote in the code to appear every hour). I'm using AlarmManager for scheduling. The first thing is the notifications does not appear at the specified hour when the app is not currently working (or during the device sleep mode), but after launching the app. And second thing is that after launching the app, notifications appear almost one by one within few seconds. I don't really understand why it happens in this way. It's quite strange for me.
Here's the NotificationUtils class, where I create my notification and put one String from Array inside setContentText() method:
package com.example.quit.notification
class NotificationUtils(context: Context) {
private var mContext = context
private lateinit var notificationBuilder: NotificationCompat.Builder
val notificationManager = NotificationManagerCompat.from(mContext)
private val CHANNEL_ID = "Notification_Channel"
init {
createNotificationChannel()
initNotificationBuilder()
}
fun launchNotification() {
with(NotificationManagerCompat.from(mContext)) {
notificationManager.notify(0, notificationBuilder.build())
}
}
private fun createNotificationChannel() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val name = "Rady"
val description = "Codzienne rady dla zdrowiejących osób uzależnionych"
val importance = NotificationManager.IMPORTANCE_DEFAULT
val channel = NotificationChannel(CHANNEL_ID, name, importance).apply {
this.description = description
}
val notificationManager: NotificationManager = mContext.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager.createNotificationChannel(channel)
}
}
private fun initNotificationBuilder() {
val sampleIntent = Intent(mContext, MainActivity::class.java).apply {
flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
}
val pendingIntent: PendingIntent = PendingIntent.getActivity(mContext, 0, sampleIntent, 0)
val data = NotificationData.notificationData.random()
notificationBuilder = NotificationCompat.Builder(mContext, CHANNEL_ID)
.setSmallIcon(R.drawable.ic_support)
.setContentTitle("Rada na dziś")
.setContentText(data)
.setPriority(NotificationCompat.PRIORITY_DEFAULT)
.setContentIntent(pendingIntent)
.setAutoCancel(true)
}
}
Second class, where I create repeating alarm:
package com.example.quit.notification
#SuppressLint("UnspecifiedImmutableFlag")
class AlarmUtils(context: Context) {
private var mContext = context
private var alarmManager: AlarmManager? = null
private var alarmIntent: PendingIntent
init {
alarmManager = mContext.getSystemService(Context.ALARM_SERVICE) as AlarmManager
alarmIntent = Intent(mContext, AlarmReceiver::class.java).let { mIntent ->
PendingIntent.getBroadcast(mContext, 100, mIntent, PendingIntent.FLAG_UPDATE_CURRENT)
}
}
fun initRepeatingAlarm(calendar: Calendar) {
calendar.apply {
set(Calendar.HOUR_OF_DAY, 20)
set(Calendar.MINUTE, 30)
set(Calendar.SECOND, 0)
}
alarmManager?.set(
AlarmManager.RTC_WAKEUP,
calendar.timeInMillis,
alarmIntent
)
}
}
Here's my AlarmReceiver, where I set next alarm after one hour in this case (:
package com.example.quit.notification
class AlarmReceiver : BroadcastReceiver() {
override fun onReceive(context: Context?, intent: Intent?) {
val notificationUtils = NotificationUtils(context!!)
notificationUtils.launchNotification()
val calendar = Calendar.getInstance()
calendar.add(Calendar.HOUR_OF_DAY, 1)
val alarmUtils = AlarmUtils(context)
alarmUtils.initRepeatingAlarm(calendar)
}
}
In AndroidManifest.xml file I only added one line in tag:
<receiver android:name=".notification.AlarmReceiver" />
And the last thing - in MainActivity class I put those three lines just after setContentView() method:
val calendar = Calendar.getInstance()
val alarmUtils = AlarmUtils(this)
alarmUtils.initRepeatingAlarm(calendar)
I'll be very grateful for any help and explanations.

It is obvious why your notifications appear immediately. In AlarmReceiver you do this:
val calendar = Calendar.getInstance()
calendar.add(Calendar.HOUR_OF_DAY, 1)
val alarmUtils = AlarmUtils(context)
alarmUtils.initRepeatingAlarm(calendar)
You want to take the current time, add one hour and schedule an alarm at that time (1 hour in the future). However, look at what initRepeatingAlarm() is doing:
calendar.apply {
set(Calendar.HOUR_OF_DAY, 20)
set(Calendar.MINUTE, 30)
set(Calendar.SECOND, 0)
}
in initRepeatingAlarm() you are setting the hour, minute and seconds to a fixed value (which is the time that the alarm originally went off). You are overwriting the time that was set in the Calendar that was passed in. In this case, when the alarm is set, the time is in the past so the alarm triggers immediately.
Regarding why the alarms do not work when the device is sleeping, the call to AlarmManager.set() is not considered "exact" and the system may delay the alarm to ensure that the device is not constantly awakened (preservation of battery). See this explanation found in the documentation.
If you want the alarm to go off at exactly this time, you need to use a different method, such as setExact(), and you will need to declare an additional permission SCHEDULE_EXACT_ALARM (if you target API level 31 or higher)

How to schedule recurring notifications in kotlin?

I've been looking for this for a couple of hours but I haven't found anything helpful. Right now, I have an activity (called other_recurringreminder) that sets a time (fomartted calendar, HH:mm; string), repetition frequency (int), repetition unit (like minutes, hours, days; string), whether it's on or off (bool), and a name (string)
In other_recurringreminder.kt, I have this function:
fun sendnotification()
{
val channelID = "channel1"
val notificationID = 1
val sharedPreferences: SharedPreferences = getSharedPreferences("sharedPrefs", Context.MODE_PRIVATE)
val builder = NotificationCompat.Builder(this, "channelID")
.setSmallIcon(R.drawable.centr)
.setColor(resources.getColor(R.color.purple))
.setContentTitle(sharedPreferences.getString("Alarm1Name_USERPREFS", "Reminder 1"))
.setContentText(getString(R.string.notif_recurringreminders))
.setPriority(NotificationCompat.PRIORITY_DEFAULT)
.setAutoCancel(true)
with(NotificationManagerCompat.from(this)) {
notify(notificationID, builder.build())
}
}
Which sends the notification when called.
How can I make it so that my app sends this notification at a time from SharedPreferences, with a title from SP, and repeats every x units from SP?
Should this function be in another kotlin file?
Can this work even after a restart, when my app hasn't yet been opened?If I want to schedule more than one notif with different values, do I need to duplicate anything?
Sorry if it's a dumb question, I'm fairly new to kotlin. and thanks!

you can use alarm manager for it.
first create a class with broadcast receiver like
class AlarmReceiver : BroadcastReceiver() {
override fun onReceive(context: Context, intent: Intent?) {
Log.d("this", "notify")
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val intent = Intent(context, AlarmActivity2::class.java)
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK)
val pendingIntent = PendingIntent.getActivity(context, 0, intent, 0)
val builder = NotificationCompat.Builder(context, "111")
.setSmallIcon(R.drawable.blue_stringart)
.setContentTitle("Alarm is running")
.setAutoCancel(true)
.setDefaults(NotificationCompat.DEFAULT_ALL)
.setDefaults(NotificationCompat.DEFAULT_SOUND)
.setDefaults(NotificationCompat.DEFAULT_VIBRATE)
.setPriority(NotificationCompat.PRIORITY_HIGH)
.addAction(R.drawable.ic_baseline_stop_24,"Stop",pendingIntent)
.setContentIntent(pendingIntent)
val notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM)
val r = RingtoneManager.getRingtone(context, notification)
r.play()
val notificationManagerCompat = NotificationManagerCompat.from(context)
notificationManagerCompat.notify(123, builder.build())
}
}
}
after that go to your activity class make 2 method and call in oncreate
private fun setAlarm1() {
var calender: Calendar
calender = Calendar.getInstance()
calender.set(Calendar.HOUR_OF_DAY, PUT_YOUR_ALARM HOUR)
calender.set(Calendar.MINUTE, PUT_YOUR_ALARM MINUTE)
calender.set(Calendar.SECOND, 0)
alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
val thuReq: Long = Calendar.getInstance().timeInMillis + 1
var reqReqCode = thuReq.toInt()
if (calender.timeInMillis < System.currentTimeMillis()) {
calender.add(Calendar.DAY_OF_YEAR, 1)
}
val alarmTimeMilsec = calender.timeInMillis
val intent = Intent(this, AlarmReceiver::class.java)
intent.setFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK)
val pendingIntent = PendingIntent.getBroadcast(this, reqReqCode, intent, 0)
alarmManager.setRepeating(
AlarmManager.RTC_WAKEUP,
calender.timeInMillis,
HERE_PUT_YOUR_HOUR * 60 * 60 * 1000,
pendingIntent
)
private fun createNotificationChannel() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val name = "Alarmclock Channel"
val description = " Reminder Alarm manager"
val importance = NotificationManager.IMPORTANCE_HIGH
val notificationChannel = NotificationChannel(CHANNELID, name, importance)
notificationChannel.description = description
val notificationManager =
getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager.createNotificationChannel(notificationChannel)
}
}
Note - Must to do(go to your app setting and give notification permission on) 1.alarmManager.setRepeating here you can use your alarm type as your wish. 2.requestcode must be unique for each alarm. 3. you must take a alarm time and keep in calender.timeInMillis which is you expecting alarm time.
still problem comments below

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

Notifications not working when app is swiped away

I'm writing a simple app that sets up to 8 random, repeating alarms, sends a notification, and then generates a quote when the user taps on the notification. This all seems to work properly when the app is running but when the app is swiped away from the recent apps, or force closed, the notifications don't work.
I've poured over my research from the last several days and can't find a solution that's current or fixes my problem. The most common thing I've seen is to use onReceive to set up a service, but my reading has shown me that this no longer works with Oreo and is outdated advice. I've also seen some stuff about foreground services, but I'm really not looking to have a persistent notification bothering the user.
I've also seen some people say to do some work in onDestroy, but that hasn't worked for me either. A lot of the stuff I've found has said that this kind of behavior is "expected behavior", as the system assumes that if an app is swiped away, the user no longer wants it doing anything. I don't want this happening and there must be some way around it, since reminders and notifications from other apps are able to come through.
Any help would be greatly appreciated, I've been struggling with this for a long time. I'll post my code for setting alarms below, as well as the code for setting up the notification channels and the BroadcastReceiver class.
By the way, my test device is a Pixel 2XL with Android 9.
//method to save preferences when the user clicks "SAVE"
private fun saveData() {
if (NOTIFICATIONS_PER_DAY > 0) {
setAlarms()
} else {
clearAlarms() //clearing if the user is removing notifications
}
val sharedPreferences = activity!!.getSharedPreferences(SHARED_PREFS, MODE_PRIVATE)
val editor = sharedPreferences.edit()
editor.putString(THEME_PREF, THEME_SELECTED)
editor.putInt(NOTS_PREF, NOTIFICATIONS_PER_DAY)
editor.apply()
Toast.makeText(context, "Settings saved", Toast.LENGTH_SHORT).show()
}//saveData method
//method to set repeating notification alarms (random times)
private fun setAlarms() {
//clearing any previously saved alarms to prevent tons of extra
clearAlarms()
calList.clear()
var hour: Int
var minute: Int
for (i in 0 until (NOTIFICATIONS_PER_DAY)) {
val hourRand = (0..23).random()
val minuteRand = (0..59).random()
hour = hourRand
minute = minuteRand
val cal = Calendar.getInstance()
cal.set(Calendar.HOUR_OF_DAY, hour)
cal.set(Calendar.MINUTE, minute)
cal.set(Calendar.SECOND, 0)
calList.add(cal)
}//for
var i = 0
for (cal in calList) {
val alarmManager = context!!.getSystemService(Context.ALARM_SERVICE) as AlarmManager
val intent = Intent(context, AlertReceiver::class.java)
val pendingIntent = PendingIntent.getBroadcast(context, i, intent, 0)
alarmManager.setInexactRepeating(AlarmManager.RTC_WAKEUP, cal.timeInMillis, AlarmManager.INTERVAL_DAY, pendingIntent)
println(i)
i++
}//for
}//setAlarms method
class BetterDays : Application() {
override fun onCreate() {
super.onCreate()
createNotificationChannels()
}
private fun createNotificationChannels() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val channel1 = NotificationChannel(CHANNEL_1_ID, "Quote Channel", NotificationManager.IMPORTANCE_DEFAULT).apply { description = "New quotes notification" }
channel1.enableLights(true)
channel1.enableVibration(true)
//channel1.description = "New quotes notification"
/* val channel2 = NotificationChannel(CHANNEL_2_ID, "New Quote!", NotificationManager.IMPORTANCE_DEFAULT)
channel2.enableLights(true)
channel2.enableVibration(true)
channel2.description = "New quotes notification" */
val manager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
manager.createNotificationChannel(channel1)
//manager.createNotificationChannel(channel2)
}
}//createNotificationChannels method
companion object {
val CHANNEL_1_ID = "quotes notification"
val CHANNEL_2_ID = "quotes notification 2"
}
}
class AlertReceiver : BroadcastReceiver() {
private var notificationManager: NotificationManagerCompat? = null
private var theContext: Context? = null
override fun onReceive(context: Context, intent: Intent) {
notificationManager = NotificationManagerCompat.from(context)
theContext = context
sendOnChannel1()
}//onReceive method
private fun sendOnChannel1() {
val title = "New Quote Available"
val message = "Come check it out!"
var index: Int = 0
if(quotesList.size != 0) {
index = Random.nextInt(quotesList.size)
}//if
quoteText = quotesList[index]
speakerText = speakersList[index]
quoteTextView?.text = quotesList[index]
speakerTextView?.text = speakersList[index]
val intent = Intent(theContext!!, MainActivity::class.java)
intent.putExtra("From", "quotesFragment")
val pendingIntent: PendingIntent = PendingIntent.getActivity(theContext, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT)
val notification = NotificationCompat.Builder(theContext!!, CHANNEL_1_ID)
.setSmallIcon(R.drawable.ic_quotes)
.setContentTitle(title)
.setContentText(message)
.setAutoCancel(true)
.setPriority(NotificationCompat.PRIORITY_DEFAULT)
.setCategory(NotificationCompat.CATEGORY_MESSAGE)
.setContentIntent(pendingIntent)
.build()
val id = createID()
notificationManager!!.notify(id, notification)
}//sendOnChannel1 method
/* //for future functionality
fun sendOnChannel2() {
val title = "Title"
val message = "Message"
val notification = NotificationCompat.Builder(theContext!!, CHANNEL_2_ID)
.setSmallIcon(R.drawable.ic_quotes)
.setContentTitle(title)
.setContentText(message)
.setPriority(NotificationCompat.PRIORITY_DEFAULT)
.setCategory(NotificationCompat.CATEGORY_MESSAGE)
.build()
notificationManager!!.notify(2, notification)
}//sendOnChannel2 method*/
//method to generate a unique ID
private fun createID(): Int{
val now = Date()
val id = Integer.parseInt(SimpleDateFormat("ddHHmmss", Locale.US).format(now))
return id
}//createID method
}//AlertReceiver class

Some chinese device with their own modified android system so when the apps are swiped from the recent app tray your app gets terminated (similar to Force Stop). And due to this every task running in the background like Services, Jobs gets killed with the app. Even High priority FCM doesn’t see the daylight in Chinese ROMs.
you can read in here : https://medium.com/mindorks/enable-background-services-in-chinese-roms-32e73dfba1a6
maybe can help ;)