As for ".. it is unnecessary for a worker fragment to start a asynctask ...", let me put it in another way. Yes, I agree a fragment without UI is not a worker thread. Why I said ".. it is unnecessary for a worker fragment to start a asynctask ..." was about the FragmentRetainInstance.java. It does not start a asynctask; It creates a new thread instead. I hope it is clearer.
Thank you for giving clear and detailed explanation about how to use a fragment without a UI. I really appreciate it! With respect to the scenario of adding multiple UI-less fragments to my activity, I would like to use UI-less fragments to perform an HTTP request, such as performing GET request to a RESTful web service. In order to provide the refresh function to users, I need to perform the request again when a corresponding event happens, such as a button click event. I could not figure out another way but only adding the same fragment to my activity. It is why I am concerned about adding multiple UI-less fragements to my activity. Is there another way to do so? 2013/2/5 Streets Of Boston <[email protected]> > ".. it is unnecessary for a worker fragment to start a asynctask ..." > I don't understand the statement above. A Fragment without a UI is not a > worker thread. It is just a Fragment without a UI. > > You can use it to tie data/tasks in the Fragment to the lifecycle of an > activity that is hosting the Fragment: > > - If you want your data/tasks to survive configuration changes (e.g. > orientation changes) that may destroy and recreate the hosting activity: > Call 'setRetainInstance(true)' in the onCreate of your Fragment. > Destroy/release/stop the data/task in your Fragment when the Fragment's > onDestroy is called. This way your Fragment's instance will survive > Activity rotations, etc. > > - If your Fragment has data/tasks that can be discarded when the screen > (activity) is no longer visible or accessible to the user: > In the onDetach of your Fragment, destroy/releases/stop the data/task, > since the user will no longer be interested in the result of the data/task. > Whether you'd like to implement this or not, depends on your app, on the > functionality of that screen. > > - You don't need to add multiple UI-less fragments to your activity > (depending on your app's needs). One is enough: > In the onCreate of your activity, user the FragmentManager to see if your > Fragment is already there (use the findFragmentBy... methods). > If it is there, all is fine. > If it is not there, create a new instance of your UI-less fragment and > add/commit it to your activity. > This makes sure you'll have only one instance of your Fragment that > survives orientation changes and such (provided that the > setRetainInstance(true) was called in the Fragment's onCreate). > > -- -- 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 --- You received this message because you are subscribed to the Google Groups "Android Developers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
