Newest Update - April 25th, 2019
New release androidx.activity ver. 1.0.0-alpha07 brings some changes
More explanations in android official guide: Provide custom back navigation
Example:
public class MyFragment extends Fragment {
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// This callback will only be called when MyFragment is at least Started.
OnBackPressedCallback callback = new OnBackPressedCallback(true /* enabled by default */) {
@Override
public void handleOnBackPressed() {
// Handle the back button event
}
};
requireActivity().getOnBackPressedDispatcher().addCallback(this, callback);
// The callback can be enabled or disabled here or in handleOnBackPressed()
}
...
}
Old Updates
UPD: April 3rd, 2019
Now its simplified. More info here
Example:
requireActivity().getOnBackPressedDispatcher().addCallback(getViewLifecycleOwner(), this);
@Override
public boolean handleOnBackPressed() {
//Do your job here
//use next line if you just need navigate up
//NavHostFragment.findNavController(this).navigateUp();
//Log.e(getClass().getSimpleName(), "handleOnBackPressed");
return true;
}
Deprecated (since Version 1.0.0-alpha06
April 3rd, 2019) :
Since this, it can be implemented just using JetPack implementation OnBackPressedCallback in your fragment
and add it to activity:
getActivity().addOnBackPressedCallback(getViewLifecycleOwner(),this);
Your fragment should looks like this:
public MyFragment extends Fragment implements OnBackPressedCallback {
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
getActivity().addOnBackPressedCallback(getViewLifecycleOwner(),this);
}
@Override
public boolean handleOnBackPressed() {
//Do your job here
//use next line if you just need navigate up
//NavHostFragment.findNavController(this).navigateUp();
//Log.e(getClass().getSimpleName(), "handleOnBackPressed");
return true;
}
@Override
public void onDestroyView() {
super.onDestroyView();
getActivity().removeOnBackPressedCallback(this);
}
}
UPD:
Your activity should extends AppCompatActivityor FragmentActivity and in Gradle file:
implementation 'androidx.appcompat:appcompat:{lastVersion}'
