Handling back press when using fragments in Android

Question

I am using Android Sliding Menu using Navigation Drawer in my application and Fragments are used in the app instead of Activities. When I open the drawer, click on an item a Fragment appears. I move from one fragment to another fragment using the following code:

Fragment fragment = null;
fragment = new GalleryFragment(selectetdMainMenu.getCategoryID());
                    FragmentTransaction ft = getFragmentManager().beginTransaction();
                    ft.addToBackStack("menuFrag");
                    ft.add(R.id.frame_container, fragment, "menuFrag");
                    ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
                    ft.commit();

In this way I can go from one fragment to another but I fail to come to the previous fragment on back button press. I managed to come up with this code to handle back press in MainActivity where Drawer is Initialized:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    super.onKeyDown(keyCode, event);
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        Fragment fragment_byTag = fragmentManager.findFragmentByTag("menuFrag");
        Fragment menuFragment_by_tag = fragmentManager.findFragmentByTag("galleryFrag");
        Fragment commentsFrag_by_tag = fragmentManager.findFragmentByTag("commentsFrag");
        Fragment dealDetail = fragmentManager.findFragmentByTag("promoFrag");
            if(commentsFrag_by_tag != null){
                if (commentsFrag_by_tag.isVisible()) {
                    Log.e("comments back  ", " clicked");
                    //menuDetailsFrag.onBackPressed();
                    FragmentManager fragmentManager = getSupportFragmentManager();
                    fragmentManager.beginTransaction().remove(commentsFrag_by_tag).commit();
                    fragmentManager.beginTransaction().show(menuFragment_by_tag).commit();
                }
            }else if(menuFragment_by_tag.isVisible()){
                Log.e("menu back  ", " clicked");
                menuDetailsFrag.onBackPressed();
                FragmentManager fragmentManager = getSupportFragmentManager();
                fragmentManager.beginTransaction().remove(menuFragment_by_tag).commit();
                fragmentManager.beginTransaction().show(fragment_byTag).commit();
            }
        }



    return false;
}

This works at times but fails most of the time. I would greatly appreciate if a better way to navigate back can be shown.

Check this one out .. http://stackoverflow.com/questions/22552653/how-to-implement-onbackpressed-intents-in-fragment — J.Ajendra, Mar 21 '14 at 07:45
add this `ft.addToBackStack(null);ft.commit();` add the fragments to the backstack and pop them. http://stackoverflow.com/questions/22550420/how-to-handle-back-event-in-drawer-list-fragment-in-android-activity/22550460#22550460 — Raghunandan, Mar 21 '14 at 07:45
I know this post is old but see my answer: https://stackoverflow.com/a/45430033/3999826 — Hamidreza Samadi, Nov 29 '17 at 13:16

score 60 · Accepted Answer · answered Mar 21 '14 at 08:15

60

I usually set an onKeyListener to the View in onResume. From what I learned you have to take care to set setFocusableInTouchMode() and requestFocus on the View.

This is a sample of what I use for this purpose:

@Override
public void onResume() {

    super.onResume();

    getView().setFocusableInTouchMode(true);
    getView().requestFocus();
    getView().setOnKeyListener(new View.OnKeyListener() {
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {

            if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK){

                // handle back button

                return true;

            }

            return false;
        }
    });
}

answered Mar 21 '14 at 08:15

super-qua

3,148
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where do I place this code? fragment or main activity> – TharakaNirmana Mar 21 '14 at 08:16
1

This worked. I added getActivity().getSupportFragmentManager().popBackStack(); to handle back press. – TharakaNirmana Mar 24 '14 at 05:02
what is the reason for having keyevent inside onresume? – TharakaNirmana Mar 24 '14 at 05:06
I'm not sure, but I think you could also put it in `onCreateView` – super-qua Mar 24 '14 at 09:23
1

@super-qua, superb solution for fragment – Hiren Patel Nov 26 '14 at 08:54
@super-qua Simple and nice solution works fine.. no need to have interface to identify back pressed..thank you – Swap-IOS-Android Jan 23 '15 at 09:25
7

This will stop working if you have a child view within the fragment that can gain focus. For example if you have a "list state" and "edit state" in the fragment, you go into the "edit state" that has an `EditText` within it, select the `EditText`, the main view will lose focus and the `onKey()` will stop functioning unless you manually regain focus of the base view. – wchristiansen Dec 01 '15 at 21:10
Imho if a child view like an EditText holds the focus, you don't want the fragment to handle the back press but the EditText itself since the context of the back press is relevant. So this is a perfectly fine behaviour – super-qua Dec 02 '15 at 09:02
great to hear that @bhavikshah28 – super-qua Feb 08 '16 at 13:22
I have added the same code inside onResume method but it is calling again and again top fragment on fragment backstack. – Chandan Wadhwa Oct 20 '16 at 06:58
I know this post is old. but see my answer: https://stackoverflow.com/a/45430033/3999826 – Hamidreza Samadi Nov 29 '17 at 13:15

score 5 · Answer 2 · edited Aug 21 '15 at 02:56

Try these methods. To me, the most useful solution is as follows:

In MainActivity:

getSupportFragmentManager().beginTransaction().replace(R.id.gif_contents, gifPageTwoFragment, "gifPageTwoFragment").addToBackStack("gifPageTwoFragment").commit();

In GifPageTwoFragment:

@Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        getView().setFocusableInTouchMode(true);
        getView().requestFocus();
        getView().setOnKeyListener(new View.OnKeyListener() {
            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK) {
                    Log.e("gif--","fragment back key is clicked");
                    getActivity().getSupportFragmentManager().popBackStack("gifPageTwoFragment", FragmentManager.POP_BACK_STACK_INCLUSIVE);
                    return true;
                }
                return false;
            }
        });
    }

score 2 · Answer 3 · answered Mar 21 '16 at 10:32

In your oncreateView() method you need to write this code and in KEYCODE_BACk condition you can write whatever the functionality you want

   View v = inflater.inflate(R.layout.xyz, container, false);
    //Back pressed Logic for fragment
    v.setFocusableInTouchMode(true);
    v.requestFocus();
    v.setOnKeyListener(new View.OnKeyListener() {
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if (event.getAction() == KeyEvent.ACTION_DOWN) {
                if (keyCode == KeyEvent.KEYCODE_BACK) {
                    getActivity().finish();
                    Intent intent = new Intent(getActivity(), MainActivity.class);
                    startActivity(intent);

                    return true;
                }
            }
            return false;
        }
    });

score 0 · Answer 4 · answered Mar 23 '16 at 13:03

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


            Fragment NameofFragment = new NameofFragment;

            FragmentTransaction  transaction=getFragmentManager().beginTransaction();
            transaction.replace(R.id.frame_container,NameofFragment);

            transaction.commit();

            return true;
        }
        return false;
    }
});

return view;

score 0 · Answer 5 · answered Sep 22 '20 at 09:26

use this (in kotlin)

activity?.onBackPressedDispatcher?.addCallback(this, object : OnBackPressedCallback(true) {
    override fun handleOnBackPressed() {
        // in here you can do logic when backPress is clicked
    }
})

i think this is the most elegant way to do it

Handling back press when using fragments in Android

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