About Android (6.0 to the last version)
I'm developing an app and we want that the user, once he accepts all the terms, don't be able to kill the process or force stop the app. Honestly, I'm completely lost right now, because on the last versions of android, and specially some brands like Xiaomi, we are having a lot of trouble with it, and we don't know how to act right now.
In the case that it could not be possible, could at least get an alert whenever the user is killing the app?
Thanks!!
It is not possible to prevent the user from killing an app. Android is a unique system where the app has no direct control over its lifecycle but the system has. The system can (and will, when required) kill the app or any of its processes at its own will. To make your app aware of these changes, the android framework provides for various callbacks such as onPause, onStop and onDestroy which are called in succession when the user kills the app.
Side Note : There is no guarantee that onDestroy() will be completely executed when the app is killed. Do not place essential code there.
Of course, you can block or try to prevent the user from closing your app by overriding the back, home and recent buttons but it is highly recommended not to do so. Even if you do so successfully, the user has other means to close your app such as rebooting their phone.
So what to do?
You are looking for a kiosk mode app. Kiosk mode is used for single purpose phones such as at a restaurant or for a cab driver. Kiosk mode apps lock down the user to only a specific app (or a specific set of apps).
For normal apps, it is not possible to prevent the user from force closing your app. You can only get alerts by checking for lifecycle changes as described above. Moreover, it is not at all recommended to change the natural behavior of the hardware buttons on android. The user can still find a way to close your app. If your app is doing something really essential which should proceed in the background, consider using a service for that instead. Also, the user can uninstall your app at anytime if they find your app being too intrusive and you won't be able to do anything in that scenario.
Tl;dr: Use kiosk mode to prevent the user from exiting the app. This will only allow the user to access your app(s) in their device.
Usually you cannot! Even if you try to disable some buttons, user can always stop app or restart device. In addition at times, the OS will stop the App. Your responsibility as a programmer is to program around this, and give the user the feel that it never stopped. If you are doing background monitoring, you will need to use service. Users will still be able to stop service. Having said that, you can set your app as a Device Administration app, see here, which may disallow stopping, but unless you are distributing internally to a company, noone will install.
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A client of mine is requesting for a very specific functionality, to keep the application always active, even after the user force kills it. He wants to ensure that the users have the application active at any time while using the device on which it is installed (the devices are managed in a constrained environment).
I've done some research on it, and already enabled background services for sending the user's location, but if they force kill the app then we are unable to send locations to the server. We've seen other apps do it, but wonder how they do it.
According to https://stackoverflow.com/a/34573169/640907 it should be possible in Android. We also found https://ssaurel.medium.com/how-to-auto-restart-an-android-application-after-a-crash-or-a-force-close-error-1a361677c0ce but I don't think this will work for our use-case, as the user can close the application without "force kill" aswell..
Anyone knows how to achieve this for a Flutter application?
I want to prevent users altering settings of my app by throwing up a splash screen to block interactions whenever they go into the device settings and open the settings page for my app.
Here's a video of another app that does this: https://inversatechnosoft.com/wp-content/uploads/2021/03/WhatsApp-Video-2021-03-05-at-7.40.24-AM.mp4
This isn't possible (at least for apps that aren't part of the system image), for good reason: that's the sort of thing malware does to take over a system.
Even if you could do that, that isn't sufficient: an app could also be uninstalled from the launcher, or other apps. You could make it harder through various tricks, but ultimately the user could simply reboot the device into safe mode and do it there.
The only cases where you could have this level of control are managed devices or within a work profile.
I don't think there is an incredibly clean way to do this, but you could start a service which regularly checks the foreground task.
You can then use the ActivityManager to get a list of all running app processes with ActivityManager.getRunningAppProcesses() and then check their importance against IMPORTANCE_FOREGROUND.
When I remove the app from the multitask list, it doesn't seem to kill the app's processes + services, but when I reopen the app, it starts from the "beginning" such as the homepage. What exactly does removing the app from the multitask list do exactly?
Generally removing an app from your multitask list is the same as quitting an active app (by hitting the back button continuously). The app stops functioning and the background processes linked to the app are killed. But, as you mentioned, it doesn't always happen because there are certain apps that require certain processes to run- for instance, closing an email app still lets it check for email and perform certain functions.
Force stopping your app is what actually kills all background processes as well, however again there are certain apps that still avoid this- this could be because they have some sort of link to the maker of the OS that allows those processes to run. For example, the Gmail app and Android OS both belong to Google, so they probably can decide how their app runs regardless of what you do as an end user.
Is it possible to have an application run on a device in such a way that it is the only application that can ever run and also prevent the user from using the operating system at all? Tapping on the Home key or Back button would not exit the application and allow the user to have access to anything. If the device boots up, only this application would run.
This would be desirable in situations where devices are installed at a business for point of sales purpose or possibly where the device acts like a terminal in public places.
You can achieve what you're describing by writing your app to replace the home screen (Launcher). From there, you control what other apps will run.
The Android SDK has a working Launcher project you can start from.
Be careful to allow some method of running a more powerful app (even if it's just enabling ADB access) -- otherwise you could leave your device in a state of needing a factory reset before it can be modified.
Yes, you can override the back and home button behaviour.
Start app, override all buttons, and the user cant exit the app, evil, but should work in your scenario.
info here
I have an app which has real time push notifications enabled. So my query is whenever any user tries to kill my app using "Advance Task Killer", my app goes into undefined state.
Undefined State: What i mean is my app doesn't gets completely terminated. The screen has data in a inconsistent state.
So is there way where i can take a user to login screen back whenever an app is killed. So that user wont see any undefined state.
Also want to know what happens to my app states after it gets killed so that i can fix the issue.
Help Appreciated.
It depends on the version of the platform. Prior to 2.2, third party applications like ATK could use an API that did the same thing as the "Force Stop" button in manage apps -- this kills all app processes, removes all tasks/activities, unregisters all alarms, removes all notifications, stops all services, etc. Basically make the application not running the same as if it was first installed, except its persistent data is still intact.
Needless to say, this tends to cause misbehavior of applications, so as of 2.2 other applications like ATK can no longer do this to your app. The API they were using is now only able to do the same thing that the out of memory killer does -- kill the application processes but only if they are in the background in a killable state. It can do no more than the normal out of memory killer, so as of 2.2 if your application is misbehaving due to an app like ATK being used on it then this is exposing an actual bug in the app that users will encounter through the normal use of their device.