What is the relationship between the life cycle of an AsyncTask and an Activity? What problems can this result in? How can these problems be avoided?

AsyncTask allows you to perform background operations and publish results on the UI thread without having to manipulate threads and/or handlers.

AsyncTask is not tied to the life cycle of the Activity. If you execute an AsyncTask inside an Activity, and the user rotates the device, the Activity will be destroyed and a new Activity instance will be created. but the AsyncTask will not die but instead goes on living until it completes. This results in 2 problems:

1. exception

   Then when the AsyncTask does complete, it updates the old activity instance rather the new activity. This can lead to an Exception:

    java.lang.IllegalArgumentException:
    View not attached to window manager if you use.
   

2. memory leak

   And because the AsyncTask maintains a reference to the old Activty, which prevents the Activity from being garbage collected as long as the AsyncTask remains alive. This results in a memory leak.

For these reasons, using AsyncTasks for long-running background tasks is generally a bad idea . Rather, for long-running background tasks, a different mechanism (such as a service) should be employed.