CODEWITHSUNDEEP
androidandroid-fragmentsbundleback-stack
heero
heero

Reputation: 1971

savedInstanceState when restoring fragment from back stack

Can I use savedInstanceState() to save the state when removing a fragment, then restore the state when I pop the fragment off the back stack? When I restore the fragment from the back stack, savedInstanceState bundle is always null.

Right now, the app flow is: fragment created -> fragment removed (added to back stack) -> fragment restored from back stack (savedInstanceState bundle is null).

Here is the relevant code:

public void onActivityCreated(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Bundle bundle = getArguments();
    Long playlistId = bundle.getLong(Constants.PLAYLIST_ID);
    int playlistItemId = bundle.getInt(Constants.PLAYLISTITEM_ID);

    if (savedInstanceState == null) {
       selectedVideoNumber = playlistItemId;
    } else {
       selectedVideoNumber = savedInstanceState.getInt("SELECTED_VIDEO");
    }
}

public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(Constants.SELECTED_VIDEO, selectedVideoNumber);
    }

I think the problem is that onSavedInstanceState() is never called when being removed and being added to back stack. If I cant use onsavedInstanceState(), is there another way to fix this?

Upvotes: 39

Views: 57322

Answers (4)

bcorso
bcorso

Reputation: 47078

The problem is that the fragment needs to have an Id or Tag associated with it in order for the FragmentManager to keep track of it.

There are at least 3 ways to do this:

  1. In xml layout declare an Id for your fragment:

    android:id=@+id/<Id>

  2. If your fragments container View has an Id, use FragmentTransaction: 

    FragmentTransaction  add (int containerViewId, Fragment fragment)

  3. If your fragment is not associated with any View (e.g. headless fragment), give it a Tag: 

    FragmentTransaction  add (Fragment fragment, String tag)

Also, see this SO answer.

Upvotes: 3

AllDayAmazing
AllDayAmazing

Reputation: 2383

I like to store the View I return in onCreateView as a global variable and then when I return I simply check this:

if(mBaseView != null) {
        // Remove the view from the parent
        ((ViewGroup)mBaseView.getParent()).removeView(mBaseView);
        // Return it
        return mBaseView;
    }

Upvotes: 5

kenyee
kenyee

Reputation: 2359

FWIW, I hit this as well, but in my case onSaveInstanceState was called properly and I pushed in my state data when a new activity fragment was brought up on the smartphone. Same as you, the onActivityCreated was called w/ savedInstanceState always null. IMHO, I think it's a bug.

I worked around it by creating a static MyApplication state and putting the data there for the equivalent of "global variables"...

Upvotes: 0

Eric
Eric

Reputation: 5402

onSaveInstanceState is (unfortunately) not called in normal back-stack re-creation of a fragment. Check out http://developer.android.com/guide/components/fragments.html#Creating and the answer on How can I maintain fragment state when added to the back stack?

Upvotes: 8

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