My app dies when switch to another app - android

I am developing two apps:
-> App A: it connects to a Bluetooth device, retrieve some data, process this data and broadcast an intent to App B
-> App B: it receives this intent and shows the results.
App A must keep running in order to keep sending data to App B.
Everything was working fine until this week when I made some visual changes and update my android device to V7.0.
Now, My App A stops (DEAD message in debugging window in android studio) when I switch to App B and see the results. If I change back to App A, current activity restarts itself and it works normally once again.
I do not get any exception or error message in android studio's debug window.
Any idea or information about this issue. I must say I have read a lot of questions and documentation but I can not find the reason of this issue.
(sorry for bad English)

Everything was working fine until this week when I made some visual
changes and update my android device to V7.0.
7.0 has introduced numerous changes aimed at improving battery life. Your App A is likely suffering from these changes, particularly if it was memory / cpu intensive, which it sounds like it might be.
App A must keep running in order to keep sending data to App B.
If that's the case, you probably want a make App A a foreground Service to ensure it keeps running.
Architecturally this probably makes more sense anyway if your use case is to have App B open while App A keeps piping data to it. The fact that your App A was not dying before was likely just lucky chance. It would have been killed by the system eventually after going into the background.

Related

Android app/activity disposes when switching to another app

I've been asked to fix an android application which has issues after switching to a newer device. The switch was from android 7/8 to 11. The application opens up google maps for navigation but very often when returned to the app all data is lost, and clicking on anything will reset it back to the startup activity. It doesn't matter which apps it switches between the issue happens with all of them.
I've tried several things:
-Disabling all battery saving options on the device
-Using OnSaveInstanceState to retain the data
-Using a backgroundservice to retain the data
The issue only occurs on actual devices, using an emulator results in no errors.
When the debugger is attached to the application it loses its connection before returning to the app. It is possible to re-attach when returning to the app but it disconnects as soon as
anything is clicked.
And best of all there's literally no error message shown anywhere.
The following comment provided the solution I needed.
You would need to start a foreground service, complete with its Notification. Even that does not guarantee that your process will remain around.
– CommonsWare Sep 1 at 12:40

Flutter app stay running while in background

I have an app I have building that is giving navigation from a location to a location. Contstantly tracking where the user is using GPS data in order to give good Directional information. Currently if a user switches from our app to another app or goes to the Android home screen, after one minute Android turns off our app for performance reasons.
I have tried using an Isolate but like flutter this gets shutdown. Next step were to use a kotlin service to handle background things but i wanted to check if anyone had done this in dart yet?
Also this is not an app that will be in the play store or on public devices. It is going on special devices that we control and are less worried about memory usage as this will be the main app ran on them.
as mentioned above in the comment by #galloper background_fetch is the thing you need, it has a method called BackgroundFetch.registerHeadlessTask(backgroundFetchHeadlessTask); where backgroundFetchHeadlessTask is a function that will keep running even when the app is close, i used this in my app to stream location info to server.

What happens when android app is "killed"

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.

Is it fine if I see my application from Settings App in the emulator has Force Close option enabled even tough I have come out of my application?

I have written a simple database program in android. It runs fine, there is no force close error. But I checked from my application from Settings App I see the Force Close option enabled, which implies that my application is still running in the background, even though I have completely came out from my application to the home screen by pressing back key. And moreover I am not using any services, alarm or broadcast things.
Can some one please guide me what may be the probable reason?. Or is it okay? Or will it crash if I put it on device?
Can some one please guide me what may be the probable reason?. Or is it okay? Or will it crash if I put it on device?
Your application is alive until Android OS needs more memory and destroys it. What I have understood does Android start destroying activities before killing the whole application. This means that your application can be alive even if you have finished your activities.
Do not worry about this; Android OS is handling this extremely well.

How to Lock(Block) an android application from starting / How to stop an android application (service) from starting at boot

I would like to know if there is a way to lock (prevent) an application from starting.
And i also would like to know if there is a way to prevent a service(application) from starting at boot of the device
...i would like to know because i would like to create an anti-malware app.
I know this question is old, but for others stumbling over it:
Autostarts is an application that can disable apps from starting at boot time. It's the best I've found to do that (it isn't resident and doesn't kill processes like a task manager, it actually parses apk packages and reads registered actions and blocks the actions you tell it to). BUT it needs root and hasn't been updated for a while (december 2011). It works on Android 2.3 on which I tested it. Because it was discontinued, I don't know if it works on newer OS versions.
It's commercial now, but that's not the point, you need a peek at the source code.
If you search a bit, you'll be able to find the source code for an older version and see how it implements the blocking system.
I would be very interested in an application that could block certain services. NOT kill, but prevent them from starting in the first place. And the list is quite big: Facebook (OrcaService, MqttPushService, MediaUploadService, BackgroundDetectionService), Twitter, Maps (NetworkInitiatedService), Yahoo Mail Sync, etc. I don't use the features that the services provide, I even disabled some of them in the app interface where possible, but they still pop up and remain resident after exiting the application.
I would like to know if there is a way to lock (prevent) an application from starting.
Not in any supported fashion. Anything that does this is malware, and the techniques for doing it are security holes.
And i also would like to know if there is a way to prevent a service(application) from
starting at boot of the device
The user can boot their phone in safe mode (I forget the exact process, but it's something like holding down the HOME key while turning the phone on).

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