Develop Reference

Notification runs randomly rather than at set time

I think I have set my alarm manager to run at 7am then at 24 hour intervals after that. It should change a image view and then send a notification. Instead it sends a notification a minute or 2 after closing or opening the app and occasionally changes the image. Can someone please explain where I went wrong? or how I can fix this?
main activity -
val mIntent = Intent(this, MyReceiver::class.java)
val calendar: Calendar = Calendar.getInstance()
calendar.setTimeInMillis(System.currentTimeMillis())
calendar.set(Calendar.HOUR_OF_DAY, 7)
calendar.set(Calendar.MINUTE, 0)
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, calendar.getTimeInMillis(),86400000, mPendingIntent,
)
MyReciver -
class MyReceiver : BroadcastReceiver() {
#RequiresApi(Build.VERSION_CODES.O)
override fun onReceive(context: Context, intent: Intent) {
val titles = arrayOf("Become inspired!", "Check out this quote!", "A new quote appeared!", "Daily quote available!")
val title = titles.random()
val notificationChannel =
NotificationChannel("My Channel", "New Quote", NotificationManager.IMPORTANCE_DEFAULT).apply {
description = "Alerts when A new daily quote is set!"
}
val builder = NotificationCompat.Builder(context!!, "My Channel")
.setSmallIcon(R.drawable.ic_stat_name)
.setContentTitle(title)
.setContentText("A new daily quote is available for viewing")
with(NotificationManagerCompat.from(context)){
createNotificationChannel(notificationChannel)
notify(1, builder.build())
}
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()
val prefs = PreferenceManager.getDefaultSharedPreferences(context)
with(prefs.edit()) {
putInt("paintings", quote)
apply()
}
}
}
Other -
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.other)
val imageView = findViewById<ImageView>(R.id.paininass)
val prefs = PreferenceManager.getDefaultSharedPreferences(this)
val quote = prefs.getInt("paintings", R.drawable.i5)
imageView.setImageResource(quote)

Like CommonsWare says in the comments, using the current day and setting the time to 7AM is usually going to put that in the past, and as the AlarmManager#setRepeating docs say:
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.
So yeah, you need to add a day if it's in the past. You can do that by comparing currentTimeMillis to Calendar#getTimeInMillis, or using its before function, or however you want to do it. Then just call add(Calendar.DAY_OF_MONTH, 1)

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)

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 ;)

Periodic Task in Background

I'm currently building an app that starts a session by sending a request to the backend. After that, the app has to send a heartbeat request every 4.5 minutes. If the app does not send a request to the backend after 4.5 minutes since the last successful request, the session will get terminated. The heartbeat request can be sent earlier which also means that the next heartbeat has to be sent 4.5 minutes after that request.
Once the user has started the session, he should be able to put the app to the background to use the device for other things.
I'm struggling with coming up with a solution that works with the background restrictions (doze mode, etc).
I'm currently running the app with a foreground service. But the requests stop after a couple of minutes if I don't use the device actively. I tried the WorkManager and the AlarmManager. But the requests keep getting delayed.
I played around with REQUEST_IGNORE_BATTERY_OPTIMIZATIONS and this seems to work but I don't want to use that approach since Google seems to really dislike apps using this permission.
I created a test app to play around with different approaches. Maybe I'm doing something completely wrong?
Service:
class MainService : Service() {
private lateinit var wakeLock: PowerManager.WakeLock
override fun onBind(intent: Intent?): IBinder? = null
override fun onCreate() {
super.onCreate()
if (Build.VERSION.SDK_INT >= 26) {
val appName = getString(R.string.app_name)
val channelName = "$appName channel name"
val channelImportance = NotificationManager.IMPORTANCE_HIGH
val channelDescription = "$appName channel description"
createNotificationChannel(this, NOTIFICATION_CHANNEL_ID, channelName, channelImportance, channelDescription)
}
val notification = createOngoingNotification(this, NOTIFICATION_REQUEST_CODE, R.mipmap.ic_launcher_round, "Content Text")
startForeground(1000, notification)
wakeLock = (getSystemService(Context.POWER_SERVICE) as PowerManager).run {
newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "MyApp::MyWakelockTag").apply {
acquire(1 * 60 * 60 * 1000L)
}
}
}
override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
intent?.action?.let {
if (it == "Heartbeat") {
val v = getSystemService(Context.VIBRATOR_SERVICE) as Vibrator
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
v.vibrate(VibrationEffect.createOneShot(500, VibrationEffect.DEFAULT_AMPLITUDE))
}
}
}
setNext()
return START_STICKY
}
private fun setNext() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
val intent = Intent(applicationContext, MainService::class.java)
intent.action = "Heartbeat"
val pendingIntent = PendingIntent.getService(applicationContext, REQUEST_CODE, intent, PendingIntent.FLAG_UPDATE_CURRENT)
val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
alarmManager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, System.currentTimeMillis() + 5 * 1000, pendingIntent)
}
}
override fun onDestroy() {
stopForeground(true)
wakeLock.release()
super.onDestroy()
}
companion object {
const val REQUEST_CODE = 101
const val NOTIFICATION_REQUEST_CODE = 100
const val NOTIFICATION_CHANNEL_ID = "notification_channel_id"
fun createOngoingNotification(context: Context, requestCode: Int, icon: Int, text: String): Notification {
val contentIntent = Intent(context, MainActivity::class.java)
.setAction(Intent.ACTION_MAIN)
.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK or Intent.FLAG_ACTIVITY_NEW_TASK)
val contentPendingIntent = PendingIntent.getActivity(context, requestCode, contentIntent, PendingIntent.FLAG_UPDATE_CURRENT)
return NotificationCompat.Builder(context, NOTIFICATION_CHANNEL_ID)
.setOngoing(true)
.setSmallIcon(icon)
.setContentTitle("Test Notification")
.setContentText(text)
.setContentIntent(contentPendingIntent)
.build()
}
#RequiresApi(api = 26)
fun createNotificationChannel(context: Context,
id: String, name: String, importance: Int,
description: String) {
val channel = NotificationChannel(id, name, importance)
channel.description = description
val notificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager.createNotificationChannel(channel)
}
}
}

I think that foreground service may be stopped as you are not executing anything inside it after you set the alarm. Foreground service keeps running if you are using it, so for making it work periodically i would put an observable that emits a value every 5 seconds for example. You only need the one emmited after 4.5 minutes but that will keep the foreground service active until you need it. Using rxjava:
Observable.intervalRange( 0 , 54, 0, 5, TimeUnit.SECONDS )
.doOnNext{
//You may not need this
}
.doOnComplete {
//heartbeat
//start this observable again for other 4.5 minutes
}
You will emit a value every 5 seconds 54 times. 54x5 = 270 seconds (what is 4.5 minutes)