Some quick answers to your questions :) 1. I use loaders mainly in fragments. Since fragments can be retained across configuration changes (setRetainInstance(true)), loaders tied to these fragments are retained across configuration changes as well. Also, delivery to your UI when data has been loaded is handled for you by loaders; you don't have to write code checking if the activity still exists if the data is delivered, etc. This makes your code less error prone and reduces the memory leak of an activity.
2. Initialize the loader in the onCreate (of a Fragment). If the fragment is retained, then you shouldn't see an empty list 'flash' when the device is rotated: The data from your loader should still be available. 3. Yes, but it depends what object initializes/loads the loader. See my previous remarks about using them in fragment that are retained. 4. Using a ContentObserver/ContentProvider would allow you to easily use CursorLoaders. 5. Again: Use a fragment that is retained and that show the 'loading' animation: When starting to load data, set a boolean that is a field in your fragment to 'true'. In onStop stop the loading... animation. In onStart, if the loading boolean is true, show the animation (again). When data has been loaded, stop the loading animation and set the loading boolean to 'false'. On Wednesday, November 14, 2012 9:38:15 PM UTC-5, Evan Ruff wrote: > > Hey guys, > > I'm beginning to bring my application out of the dark ages (API 7) up to > the more recent stuff and I'd like to migrate from my current Singleton > data provider to something like the Loader paradigm. I had a couple of > question. Currently, when the Application starts, I pull all of my objects > out of the database and hold them in a singleton User object on the > Application. The Activities then pass around ID references which query the > singleton for values. This breaks down rather dramatically when the > application is terminated and doesn't really jive well with "the Android > way." I've started to do some testing with loaders and have based my test > implementation off the follow tutorial: > > http://www.androiddesignpatterns.com/2012/08/implementing-loaders.html > > Couple Questions: > 1. Are loaders special? Are they handled differently from a LifeCycle > perspective or is it simply a more streamlined way of doing loading in an > AsyncTask then returning it to the Activity? > > 2. There always seems to be a nasty flash of an empty list on my > Activities. Should the onResume check for a load and load immediately? > (deliverResults?) > > 3. Do the loaders save state in an onSaveInstanceState sort of way? > > 4. I'm a little foggy on the ContentObserver. My data is backed up by the > SQLlite DB... is a ContentObserver "better", or should I just manually > invoke BroadcastReceivers when my application pulls down new data? > > 5. How should I handle loading animations in the Activity? Traditional way > of start/stopping the "Loading" animation? My question is around when... > show ProgressBar in onResume and hide it on onLoadFinished? > > Thanks for any pointers! > > E > -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
