I have a task which I need to run in the background in my Android app. It reads data over the network and populates a database. It can take several minutes to run.
Once it’s started, it needs to complete successfully without interruption. (Otherwise I’ll end up with a broken half-populated database.) I realise I can never guarantee it will always complete, but I want to make it as hard as possible for the system to kill off this task. For safety I guess I will have it populate a temporary database, and then only swap out the old database for the new one on successful completion of the import.
It’s a modal operation; it does not make sense for the user to be interacting with the app while the import is in progress.
My first attempt is using an ASyncTask with a Progress dialog to achieve the modality, but this obviously breaks the “don’t interrupt” requirement. I could work around the screen-rotation issue with ASyncTasks, but I don’t think that goes far enough.
At the moment I’m not sure if this should be an ASyncTask, a Service, an IntentService, some combination of these, or something else entirely. Can you help me decide?
You are better off with services in that case. The Android runtime will leave it alone working as long as enough memory is available. In the case it kills the service, you can save the state in a bundle, and the system will restart the process as soon as possible, so you can resume the process, if possible for your solution:
Android Fundamentals, Service Section
Then it is easy to communicate with the service, like showing the progress/ notifications etc, using a handle registry like proposes by Mark Bredy in his Android Service Prototype