I'm aware that a Service's onDestroy() method may never be called but can someone tell me when such a scenario might occur? I'm especially interested in whether it's possible for a Service to be killed, yet its VM would continue to run.
I ask because I have a service that registers ContentObservers in the service's onStartCommand() method and unregisters them onDestroy(). If the service's onDestroy() method was never called because the whole VM was killed (along with the observers it created,) that would be fine. But I'm wondering if it's possible for a service to "go away" without onDestroy() being called, while the observers it created would live on and continue to receive changes.
I'm aware that a Service's onDestroy() method may never be called but can someone tell me when such a scenario might occur?
Here are three off the top of my head:
If the user Force Stops you from the Settings app
If Android needs RAM in a hurry (e.g., to process an incoming phone call) and elects to terminate your process to free up that RAM
You terminate the process from DDMS
Also, if your service crashes with an unhandled exception somewhere, Android may consider the service to be defunct and skip onDestroy(). I'm not sure about this one, as I haven't specifically tried it.
But I'm wondering if it's possible for a service to "go away" without onDestroy() being called, while the observers it created would live on and continue to receive changes.
Other than the unhandled-exception possibility I mention above, I am reasonably certain that if the process will be terminated in the conditions where onDestroy() is not called.
Also if the app is reinstalled/updated , ondestroy() is never called.
来源：https://stackoverflow.com/questions/14147846/situations-when-a-services-ondestroy-method-doesnt-get-called