What is the best way to do long running task in android?

I am new to android application development. I understand that in android, long running operations should not happen in main thread and we can use Async Task for doing the same. To do the following operations,

Download a file (> 5 MM) from server.Make a http/s call from the application.Make any call other than http (example - voice call) from the application.

is Async Task the best approach or do we have any other options in android for any of the above tasks?

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