What happens when android app is "killed"

Question

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.

Answer 1

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.