Develop Reference

I want to schedule notification on specific date should i use workmanager?

I am developing one app where I want to schedule notification on a specific date and time.
Specifically on a date when the app trial is over. I am giving a 4-day app trial to the user and when the trial is over.
ex: the user installs the app on 05-03-2020 then the app will give notification on date 08-03-2020
so should I use the work manager to schedule notification or any other option in android?

WorkManager is intended for tasks that are deferrable - that is, not required to run immediately and required to run reliably even if the app exits or the device restarts. For example:
Sending logs or analytics to backend services
Periodically syncing application data with a server
Alarms (based on the AlarmManager class) give you a way to perform time-based operations outside the lifetime of your application. For example, you could use an alarm to initiate a long-running operation, such as starting a service once a day to download a weather forecast.
Alarms have these characteristics:
They let you fire Intents at set times and/or intervals.
They operate outside of your application, so you can use them to
trigger events or actions even when your app is not running, and even
if the device itself is asleep.
So for your requirement, you should be using an AlarmManager instead of WorkManager as you only need to deliver a notification.

Android reschedule alarmmanager alarm when app is killed

I've developed an app to schedule multiple local notifications to remind users to do something. Every month in the current year there should an notification be raised.
These local notifications are scheduled using an "AlarmManager". A notification is created and raised in the OnRetrieve of a "BroadcastReceiver".
It works all fine until the app is terminated (by user) or the device is rebooted.
After some research I found the solution to reschedule the alarm / local notifications if the device is rebooted => using a BroadcastReceiver with "ActionBootCompleted" as intent filter and then reschedule the notifications in the "OnReceive".
Unfortunately I can't find a decent solution to reschedule the alarm / local notifications if the app is terminated.
What is the best approach for this case?

Try to run this as a background service. When the user opens up the app for the first time, call the service OnCreate(). Make sure the service is START_STICKY so it cannot be stopped unless you explicitly tell it to. Then place your AlarmManagers inside the service.

Android background Services, Alarms and preserving object reference after application restart

I'm developing a little Android app, that needs to run a background process, used to start a remote connection periodically (for example, to check if there is new data on the server). This process obviously needs to work also if the application activity is not running at the moment.
As I can see in documentation, there are two types of approach to develop a scheduled background process in Android, working also when the application is closed.
Services
Alarms
The first one is not so good for my requirementes, because it can be killed by OS in case of low memory, so it is useless for me. startForeground() is not so good because I want the process is silent.
Alarm is ok, because it can't be killed by the OS, so it can work indefinitely. But... If I schedule an Intent with the AlarmManager, how can I preserve a reference to the Intent, surviving at application restart?
For example, if I want to cancel, or reschedule the Alarm, I need the reference to the initial Intent to cancel it thorugh the "AlarmManager.cancel(Intent i)" method. But if the application was restarted by the user, how can I obtain a reference to the initial Intent that was used to start the alarm?
Is there another way to stop an alarm if the launching application was restarted?

about alarms, you can cancel using the intent characteristics, so you don't need a reference to the original intent. In any case, the alarms mechanism still need you to run something on a service.
In any case, you missed another possible solution: SyncAdapter. Its purpose is to sync with servers, but you can do whatever you wish in the code, and it's unlikely the OS will kill it, as opposed to the other solutions you've mentioned.
Sadly even now it lacks on documentation and samples, but I think it can fulfill your needs. Here's what I've found

yes, note that cancel is looking for a PendingIntent, not an Intent per se.
so
PendingIntent pendingIntent = PendingIntent.getBroadcast(this, R.string.some_string, new Intent(this, InitialIntent.class), 0);
AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
alarmManager.cancel(pendingIntent);
gets you where you want to be.
note that I'm not getString'ing that string, that's becasue I want a unique Id/request code for this intent that I'm not going to screw up copypasting; I reference the same number when creating the alarm in InititalIntent.

This question was just answered, here:
How can I get the context of other activity?
Just cancel the intent you scheduled

Your best bet would be to make use to push notification (via GCM), whenever something new is available on the server. I am working on similar application where data can be pushed from one side (producers) and needs to be pushed to the consumer apps.
You need to look at BroadcastReceiver and GCM specific communication model. Hope this helps

Stop AlarmManager when app is accidentally closed

I have a question regarding AlarmManager and how to stop it when the app is accidentally closed.
My AlarmManager is repeating its alarm every 30 minute. Now when a user accidentally closes the app the alarm is still working. That is not so bad, because for a certain time it is intended to do so, but as soon as the user wants to stop the repeating alarm it is not working anymore ( a feature of the AlarmManager ). So, the user has to reboot Android.
Is there another way to stop the AlarmManager although the app is closed?
Maybe, someone has an example for me?
Thank you very much!
Best Regards,
Bernd

You have to cancel your alarms yourself. Just call alarmManager.cancel(pi) where pi is a previously created pending intent that you used to schedule the alarm.
If you don't need the pending intent anymore, you can also cancel it by calling pi.cancel().
Another possibility is to add a check on your alarm broadcast receiver to ignore the scheduled alarms in certain situations where you don't need them anymore. This has the drawback of consuming more battery because the phone will wake up to trigger the alarms.

AlarmManager with BroadcastReceiver - how is it meant to work?

I'm trying to make a task schedule app and I made an Alarm app trying to learn how to do that part at least. It uses AlarmManager and it makes an alarm go off at a time chosen by a TimePicker. But it doesn't work when the emulator is turned off and on again.
So I'm trying to use BroadcastReceiver but I don't understand any of the guides...I mean am I supposed to set the intent that the alarm manager does to the BroadcastReciever? Or can I just start up the app and then the alarm exists again or what? How are the alarms stored in android?

But it doesn't work when the emulator is turned off and on again.
That is the correct behavior -- AlarmManager's schedule is cleared on a reboot. You need to specifically register to receive the ACTION_BOOT_COMPLETED broadcast, in order to re-establish your alarm events after a reboot.
I mean am I supposed to set the intent that the alarm manager does to the BroadcastReciever?
Well, if you are using a _WAKEUP-style alarm, the recipe is to use a getBroadcast() PendingIntent with AlarmManager, where the BroadcastReceiver is either a WakefulBroadcastReceiver (and follows those instructions) or passes control to my WakefulIntentService.
I have somewhat-contrived examples of using WakefulIntentService and WakefulBroadcastRecevier.
How are the alarms stored in android?
AFAIK, they are held in the memory of a core OS process and are not persisted.