Can't change ActionBar title in a nested fragment

Question

There is a fragment, and it's xml markup contains ViewPager . Within this fragment it's necessary to implement navigation in other fragments by swipe.

public class MainFragment extends Fragment {

    private View view;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.main_fragment, null);

        ViewPager viewPager = (ViewPager) view.findViewById(R.id.viewPager);
        viewPager.setAdapter(new MyAdapter(getChildFragmentManager()));

        return view;
    }

    public class MyAdapter extends FragmentStatePagerAdapter {
        public MyAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            Fragment fragment = null;
            switch (position) {
                case 0:
                    fragment = new Fragment1();
                    break;
                case 1:
                    fragment = new Fragment2();
                    break;
            }
            return fragment;
        }
    }
}

Everything works well. The problem is that the Fragment1 isn't possible to set own title using setTitle() method: the title remains the same .

public class Fragment1 extends Fragment {
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.fragment1, null);

        getActivity().setTitle("Fragment 1");

        return view;
    }
}

What has gone wrong, and why the title of the parent Activity, which contains the MainFragment , doesn't change when I call setTitle() ?

Thanks!

Answer 1

您可以使用以下方法从片段中更新活动标题：

((AppCompatActivity)getActivity()).getSupportActionBar().setTitle("My custom title");