JAVA

android back navigation

@Override
public boolean onOptionsItemSelected(@NonNull MenuItem item) {
  int itemId = item.getItemId();
  if (itemId == android.R.id.home) {
    // force up navigation to have the same behavior as temporal navigation
    onBackPressed();
    return true;
  } else {
    return super.onOptionsItemSelected(item);
  }
}

android back navigation

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()
    }
    ...
}