Actually the big reason for using a Bundle is because this needs to be saved as part of the saved instance state of the activity. The Bundle class provides a data structure that is Parcelable (can be saved) and automatically takes care of the marshalling/unmarshalling for you (so the app developer won't need to deal with that complexity).
If you use a constructor that takes an int, you will then need to write the code in onSaveInstanceState() to store the int and retrieve it in onCreate(). Since you are going to be dealing with bundles, anyway, you might as well just have it in a bundle up-front and let the framework take care of the saving and restoring. In fact the whole arguments API was added to fragment just to reduce the amount I was seeing that you had to write that save/restore boilerplate code. Of course if you don't really care about retaining your arguments across instances, then there is no reason to use the formal arguments bundle and go ahead and have a constructor with the typed arguments. That said, if you think this is the case, there is probably a 90% chance you actually aren't realizing that you *do* need to have those arguments saved so will run into problems later. Also you need to be aware that a fragment needs to have an empty constructor so it can be re-created later from saved state, so if you do have a constructor with arguments, you need to be sure to also explicitly write an empty constructor. On Sun, Feb 13, 2011 at 2:32 PM, davemac <[email protected]> wrote: > I think I understand the logic behind using Bundles to pass in and > store values associated with a Fragment, but I wondered if someone > could validate my understanding. > > I believe that it makes sense to use a Bundle to pass in initial > values at the time of construction of a Fragment for a number of > reasons: > 1) Bundles are a simple way to pass in an arbitrary number of > arguments of different types, so the pattern of using Fragments is the > same for everyone. This makes understanding them easier. > 2) The arguments Bundle on a Fragment (setArguments, getArguments) > is a convenience over having to create class member fields to keep > track of the specifics of a Fragment object. > 3) It is simple to take an extras Bundle from an inbound Intent > and pass it to a Fragment's creation logic. > > This doesn't mean you always need to use a Bundle when creating a > Fragment, but if you have a few or more values to pass in, a Bundle > makes a lot of sense. Are there other reasons why you'd want to use > Bundles in this way? Or situations where you wouldn't? The Shakespeare > example that Dianne blogged about recently used a Bundle for a single > int value. Was this more for demonstration purposes? Or would it have > been acceptable to simply use a constructor that takes an int, and > save it in a member field for later? Thanks! > > -- > 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 > -- Dianne Hackborn Android framework engineer [email protected] Note: please don't send private questions to me, as I don't have time to provide private support, and so won't reply to such e-mails. All such questions should be posted on public forums, where I and others can see and answer them. -- 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
