在Fragment.onCreate（）中代替onActivityCreated（）中启动加载器是个好主意吗？

Question

Is it a good idea to start a loader in Fragment.onCreate() instead of onActivityCreated()? I am thinking about performance. I'd like data loading and fragment UI rendering to happen in parallel. By starting a loader in Fragment.onCreate(), data loading can start earlier than in Fragment.onActivityCreated(). Is there any drawback of this approach? Thanks.

Answer 1

You can initialize a loader in onCreate if the fragment isn't retained across Activity re-creation (setRetainInstance(true) is NOT called). If it's retained across Activity re-creation (setRetainInstance(true) is called) you'd want to init the loader in onActivityCreated because onCreate won't be called after a configuration change (eg screen rotation).

You HAVE to init the loader after a configuration change because even with setRetainInstance(true) the callback methods passed in initLoader or restartLoader won't be retained and need to be set again or you won't receive callbacks like onLoadFinished() which would very likely break your app.

There's no drawback of initializing a loader in onCreate if the fragment isn't retained across configuration changes, just make sure that you don't update the ui too early (onLoadFinished could be called even if the layout hasn't been inflated yet).