从FragmentPagerAdapter中的片段更新活动标题

Question

I have v4.ViewPager inside Activity and use SlidingTabLayout from google's examples SlidingTabBasics. The problem I encounter is that each fragment retrieved from getItem(position) in v4.FragmentPagerAdapter has to refresh activity title . I have already learnt the hard way that FragmentPagerAdapter causes fragments to have really weird life callbacks so I can't probably use onResume or onStart . I noticed though that onCreateOptionsMenu(menu,inflater) gets called exactly when I want to refresh activity title. Is there a callback to supply actions when ViewPager has settled the fragment and it should change activity title? Setting callback on ViewPager.onPageSelected(position) is inconvenient because I want this information to be propagated from fragment, not to fragment.

Currently I 'steal' onCreateOptionsMenu(menu,inflater) to do the work for me but it causes optimisation issues when no menu should be inflated but I still want the fragment to be able to affect activity title.

Answer 1

Have you tried this code in your fragment:

if(getActivity() != null){
   getActivity().setTitle("new title");
}

Take into consideration that getActivity() will be null if the fragment is not yet attached to the activity.

Godspeed.

Answer 2

You can do this in different ways. You can use interfaces in fragments that can be implemented by activity. But the drawback is, if you do have large number of fragments you must implement all of them.