set OnBackPressed in Fragment

Question

I am having 4 fragments.They are consists of HomeFragment, Rainfall, rainday, and yieldFragment. If right now i am on Rainfall fragment, then i press backbutton, i want the fragment will come back to Home fragment(as a default). But right now my applicaton situation is when press backbutton, the application was closed. I've tried by using onBackpressed, but i think my onBackPressed was not work properly.

What should i do for this situation..?Please anyone can answer. i've tried this...

  public void onBackPressed() {

        fragment=new HomeFragment();}

Please help me if anyone knows.

Possible duplicate of [How to implement onBackPressed() in Fragments?](http://stackoverflow.com/questions/5448653/how-to-implement-onbackpressed-in-fragments) — H Raval, Oct 11 '16 at 09:07
Similar problem solved [here](https://stackoverflow.com/a/46425415/6831069) Enjoy — Maxime Jallu, Oct 02 '17 at 22:16

score 2 · Answer 1 · answered Aug 19 '21 at 13:32

If I'm not mistaken, all you have to do is paste the following line of code into the onViewCreated fun of the relevant fragment.

        val callback = object : OnBackPressedCallback(true){
            override fun handleOnBackPressed() {
                "your_code_here"
                "If you leave this blank, the back button will not work."
            }
        }

        requireActivity().onBackPressedDispatcher.addCallback(callback)

score 0 · Answer 2 · answered Oct 11 '16 at 09:26

first of all at the time of switch in to fragment ,used #replace rather then #add new fragment from your container activity.

second inside your #inner fragments ,override onResume() as depicted below. It will give you call back of device back button .

@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) {

                HomeFragment fragObj = new HomeFragment();

                getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, fragObj)
                        .commit();

                return true;
            }

            return false;
        }
    });
}

can i ask you what the refer of (R.id.fragment_container)? :) — Sasya, Oct 12 '16 at 02:35
R.id.fragment_container ,is the id of your container activity (main activity / home activity )in which all fragments will be loaded.Normally we used frameLayout as a container in side main activity and this id refers that frameLayout. — Radhey, Oct 12 '16 at 04:58

score 0 · Answer 3 · answered Oct 11 '16 at 09:51

Add your fragment transaction to the back stack, like so:

getSupportFragmentManager().beginTransaction()
           .replace(R.id.your_fragment_id, RainfallFragment())
           .addToBackStack(null)
           .commit()

If you're extending AppCompatActivity and using the latest version of support library, you don't have to do anything else. But if that's not the case, override onBackPressed() in your activity:

@Override
public void onBackPressed() {
     if (getSupportFragmentManager().getBackStackEntryCount() > 0) {
           getSupportFragmentManager().popBackStack();
     } else {
           finish();
     }
}

set OnBackPressed in Fragment

3 Answers3