Develop Reference

Android Oreo: Is there any way to auto - start the application on mobile reboot?

I am developing an application for a business entity. That application should run in the background in every employees' mobile phone. Employees are mostly salesman. The application basically detects location changes and suggest the salesman where they might visit. A kind of reminder application. It also lets other salesmen see where are their teammates.
Right now I am using a foreground activity and it works fine till the system forcefully doesn't kill the service or the phone doesn't reboot due to manual activity or battery discharge.
Ones the application is closed, as of now, the managers in the firm needs to call salespeople to turn on the application once, as on application start it automatically turn on its foreground service. But this is really an extra burden on the management team which can be automated.
I am ok to have any settings based or code based solution. One solution is to root the phones of salespeople and install some extra utility app or write the code based on root APIs, but this will be too much for this simple task.

THe permission RECEIVE_BOOT_COMPLETED was not added properly in the manifest. After adding the permission it worked calmly. In on receive method of the broadcast receiver, I am starting the foreground service.

At the moment, the best way is to use WorkManager https://developer.android.com/topic/libraries/architecture/workmanager/ Yes, it still alpha, but works very good.
From other side, you could work on automating the task "managers in the firm needs to call salespeople to turn on the application once". I mean, an app/backend could automatically call the salesman (with some pre-recorded message) or send SMS to them.

broadcast receiver prei-nstalled apps

I know that in applications developed by third parties to get on google play, BroadcastReceiver not begin to run until the user enters the application.
I would like to know what happens in applications that are pre installed on the phone, because I am developing an application of this type. They start to listen from the beginning or require the user to enter the application?

System apps receive broadcasts, even if they are in force stopped state or have not been started even once
Edit :
PackageManagerService has a ActivityIntentResolver which resolves all the broadcasts. So if you check the override for isFilterStopped, it is excluding system apps from stopped packages.
Below is the comment you can search in AOSP:
// System apps are never considered stopped for purposes of
// filtering, because there may be no way for the user to
// actually re-launch them.

How to lock (other) apps with password?

I've seen some "app locking" solutions in the Google Play store and I was wondering how those apps work. I'd like to build something similar.
I realize that this might require some special permission or maybe request the app to be added as device administrator.
Is there some broadcast that is triggered just before an app is launched that I can intercept and do some action (e.g. launch an activity that will request the user to fill a password)? I've read some lengthy discussions how this is not a good idea and the only idea is to have a background service that will continuously poll the running processes and check for changes, but I think retrieving this list every second and checking it for chances is not good for the battery and I think other app locking apps out there must be using a different approch.
If possible, without the need for a rooted phone.

Stop Android Service from another package

Before someone tells me this cannot be done, I have done plenty of research on why on process cannot interfere with one another and under what conditions this is possible. Our problem is that the Bluetooth support between devices is inconsistent and the solution on some devices is to stop the existing Bluetooth service and run a separate app (BlueFTP) which is then able to listen on the freed port and manage OPP communication.
android.permission.RESTART_PACKAGES permission plus ActivityManager.restartPackage() doesn't work as it simply restarts the offending package.
Process.killProcess does not work for the obvious reasons (read the API)
android.permission.KILL_BACKGROUND_PROCESSES permission plus ActivityManager.killBackgroundProcesses() is ignored because (I believe as per the API) the Bluetooth app is not considered a background app and therefore not eligible to be killed.
Currently if a client is having an issue with a specific phone, we get them to go to the running apps and force stop the offending OPP Service before refreshing BlueFTP so that the port listener starts. The offending service has more than one possible name depending on the phone and Android version.
So. The process is currently manual but I was hoping there would be a way to achieve this via code mirroring the force stop option in settings. A lighter option could be to assist in opening the settings for that service rather than needing to explain to clients how to get there, but I'd prefer a complete solution if one is available.
Note that while our the dev phones have root access, the client phones will not.

You can use implicit intents for your services in other apps to close them. It wouldn't need extra permissions as well, unless your service enforces a permission for it's access.
Oh, I overlooked the fact that it's a third party app. In that case, you can't really do much. Sorry.

What's the mechanism of locking access to selected applications in Android?

I'm trying to find out how applications like Perfect App Protector or Smart Applock Free work.
What mechanism is used?

These applications use a service to monitor whether a new application is trying to launch or not.
It can be done in several ways. If running application matched with the configured application then it is sent back to the background by the service and may ask for lock code, password as you configured earlier. If it matches then you will get the application on the foreground. Otherwise it kills the process from being executed.