How to implement onBackPressed for Android Fragment?

Question

I want to implement custom onBackPressed methods for all my fragments which are included in my Main activity. But I am not getting a hook when my device back is pressed. I tried to implement few stuffs available in SOF, but none of them work properly. Please Help!

I tried this in onCreateView:

rootView.setFocusableInTouchMode(true);
rootView.requestFocus();
rootView.setOnKeyListener( new OnKeyListener()
{
@Override
public boolean onKey( View v, int keyCode, KeyEvent event )
{
    if( keyCode == KeyEvent.KEYCODE_BACK)
    {
        return true;
    }
    return false;
}
} );

please have a look at this link http://stackoverflow.com/questions/7992216/android-fragment-handle-back-button-press — Somasundaram NP, Sep 19 '15 at 10:13
Thanks @Rajsundar. But this solution doesn't work for the following case: A-B B-C Now the onBack of fragment B does not get called. — pagalpanda, Sep 19 '15 at 10:22

Amey Bawiskar · Answer 1 · 2015-09-21T05:22:21.920

Use below code hopefully this code will help you.

 rootView.setOnKeyListener(new View.OnKeyListener() {
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {


            if (keyCode == KeyEvent.KEYCODE_BACK) {


                backFlag = backFlag++;

                if (backFlag == 2) {
                    getActivity().finish();
                }
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                backFlag = 0;

                return true;
            }
            return false;
        }
    });

score 0 · Answer 2 · answered Sep 19 '15 at 10:11

0

Same issue here. I solve this by setting actionbar title to fragment and then check onBackPressed which fragment is currently visible by checking the title of ActionBar. Its not proper solution but it works for me perfectly. if u have any question tell me. Hope it works for u. Thanx

answered Sep 19 '15 at 10:11

akhil batlawala

1,066
1
10
30

This way is so easy you just have to give proper title to particular fragment and it works. if you need code tell me – akhil batlawala Sep 19 '15 at 10:15
Thanks Akhil. That will work. But few of my fragments have same ActionBar title, and based on few conditions I need to set the title bar of the fragment to which I will be navigating to, on back pressed. – pagalpanda Sep 19 '15 at 10:20
You have to Set Unique Title for fragment then it works. Please give Reputation and mark as correct answer please. So other person use it – akhil batlawala Sep 19 '15 at 10:22
are you adding this to onBackPressed in the Parent activity? – pagalpanda Sep 19 '15 at 11:21
Yes. first set the title of fragment while displaying the fragment – akhil batlawala Sep 19 '15 at 11:23
Please give reputation. I need that – akhil batlawala Sep 19 '15 at 11:23
For me the onBackPressed method is not getting called for all my fragments! :( – pagalpanda Sep 19 '15 at 11:29
you have to set my code on your activities OnBackPressed. Which have your fragments in child. Any Error or something?? – akhil batlawala Sep 19 '15 at 11:36
The issue is probably because I am just adding fragments, not replacing them. – pagalpanda Sep 19 '15 at 11:39

score 0 · Answer 3 · answered Sep 19 '15 at 14:47

public interface OnBackPressedListener {
  boolean onBackPressed();
}

public interface OnBackPressedNotifier {
  void registerOnBackPressedListener(OnBackPressedListener listener);
  void unregisterOnBackPressedListener(OnBackPressedListener listener);
}




public class SampleActivity extends Activity implements OnBackPressedNotifier {

  List<OnBackPressedListener> onBackPressedListeners = new ArrayList<>();

  @Override
  public void registerOnBackPressedListener(OnBackPressedListener listener)   {
    if (!onBackPressedListeners.contains(listener))
        onBackPressedListeners.add(listener);
  }

  @Override
  public void unregisterOnBackPressedListener(OnBackPressedListener listener) {
    if(onBackPressedListeners.contains(listener))
        onBackPressedListeners.remove(listener);
    }

  @Override
  protected void onDestroy() {
    onBackPressedListeners.clear();
    super.onDestroy();
  }

  private boolean notifyOnBackPressed(){
      boolean handledByFragment = false;
      for (OnBackPressedListener listener : onBackPressedListeners){
          handledByFragment = listener.onBackPressed();
          if (handledByFragment)
              break;
      }
      return handledByFragment;
  }

  @Override
  public void onBackPressed() {
      if (!notifyOnBackPressed())
          super.onBackPressed();
  }

}

public class SampleFragment extends android.support.v4.app.Fragment implements OnBackPressedListener {

@Override
public void onAttach(Context context) {
    super.onAttach(context);
    ((OnBackPressedNotifier)getActivity()).registerOnBackPressedListener(this);
}

@Override
public void onDetach() {
    ((OnBackPressedNotifier)getActivity()).unregisterOnBackPressedListener(this);
    super.onDetach();
}

@Override
public boolean onBackPressed() {
    // Handle onBackPressed
    return false;
}

This doesn't work when I have fragments added(not replaced). — pagalpanda, Sep 19 '15 at 17:55

score 0 · Answer 4 · answered Feb 23 '21 at 11:08

0

You can use the new API.

activity?.onBackPressedDispatcher?.addCallback

answered Feb 23 '21 at 11:08

How to implement onBackPressed for Android Fragment?

4 Answers4