Replacing fragments in an activity not calling onA

问题:

So I have this piece of code here, I am creating a new Fragment and replacing it with another fragment. That works well. However I have notice that on the first line the constructor is being called but the onAttach(), onCreate() etc are not. If I were to uncomment the second line it won't work as updateItem(URL) requires a webView that is initiated in the onCreate() function.

DetailViewFragment detailFragment = new DetailViewFragment();
//detailFragment.updateItem(URL);
FragmentTransaction ft = getFragmentManager().beginTransaction();
ft.replace(R.id.displayList, detailFragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.addToBackStack(null);
ft.commit();

Would appreciate any help that will get that to work with the second line uncommented.

回答1:

The onAttach(), onCreate(), etc. will not be called until the FragmentManager has actually committed the change. So, some time after commit() is called on the transition. If you need to pass the URL to the Fragment from the start, add it to the fragment's argument bundle before you call commit(). Then you'll be able to get access to the URL in your onCreate() or other lifecycle methods. So you'll want something like this:

DetailViewFragment detailFragment = new DetailViewFragment();
Bundle args = new Bundle();
args.putString(DetailViewFragment.INIT_URL, URL);
detailFragment.setArguments(args);
ft.replace(R.id.displayList, detailFragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.addToBackStack(null);
ft.commit();

Now in your onCreate() you can call getArguments() to get the bundle and retrieve the URL which was passed by your activity.

回答2:

API Level 23 onAttach(Context context) works
API Level 22 onAttach(Activity activity) works

Implementing both methods worked for me:

@Override
public void onAttach(Context context) {
    super.onAttach(context);
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
}

回答3:

Another solution would be to call getSupportFragmentManager().executePendingTransactions(); just after the commit. Beware that the transcation will be synchronous then.