How can I replace fragment inside a fragment?

Question

I have an Activity with a ViewPager, each page of the ViewPager has a Fragment.

Inside my Screen3Fragment I have a LinearLayout ( lly_fragments ) where I am showing some other fragments. I start by showing the fragment Screen3_1

public class Screen3Fragment extends Fragment {

    private FragmentManager manager;
    private FragmentTransaction transaction;


    public static Screen3Fragment newInstance() {
        final Screen3Fragment mf = new Screen3Fragment();
        return mf;
    }

    public Screen3Fragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View v = inflater.inflate(R.layout.fragment_screen3, container, false);
        Screen3_1Fragment frag31 = new Screen3_1Fragment();
        manager = getChildFragmentManager();
        transaction = manager.beginTransaction();
        transaction.add(R.id.lly_fragments,frag31,"frag31");
        transaction.addToBackStack("frag31");
        transaction.commit();
        return v;
    }

}

This works fine without problems. Problem comes when, from within frag31 (which is inside Screen3Fragment), I want to call fragt32 , for that I do the following.

public class Screen3_1Fragment extends Fragment {

    private ImageButton imgbt_timer;
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

        View v = inflater.inflate(R.layout.fragment_screen3_1,container,false);
        imgbt_timer = (ImageButton) v.findViewById(R.id.bT_scr31_timer);
        imgbt_timer.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                getChildFragmentManager().beginTransaction()
                                            .replace(R.id.lly_fragments, new Screen3_2Fragment(), "frag32")
                                            .commit();
            }
        });


        return v;
    }
}

As I read in other answers, the line transaction.replace should do the trick and replace the existing frag31 by the given frag32 inside the same given container lly_fragments .

However, I get java.lang.IllegalArgumentException: No view found for id..... I am not sure why.

Answer 1

getFragmentManager() will return always attributes from parent, in most cases the activities. getChildFragmentManager() wil return parent attributes (in your case, Screen3Fragment attributes). It should be used when you add a fragment inside a fragment.

In your case, Screen3Fragment should be added using getFragmentManager() and Screen3_1Fragment should be added using getChildFragmentManager() because Screen3_1Fragment is Screen3Fragment child. Screen3Fragment is the parent.

I recomand you to use always getFragmentManager() with add method, not replace because your parent will be the same.

getChildFragmentManager() can be used when you add a ViewPager inside a fragment.

Answer 2

You can use the callback, as following : that worked for me, I hope my answers helps you

1) create a interface

  public interface ChangeFragmentListener {

    void onChangeFragmentLicked(int fragment);
}

2) implement the interface and transaction methods in your activity:

      public class MainActivity extends AppCompatActivity implements ChangeFragmentListener {


        FragmentTransaction fragmentTransaction;
        Fragment1 fragment1;
        Fragment2 fragment2;


        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main2);

            fragment1 = new Fragment1();
            fragment1.setChangeFragmentListener(this);

            fragment2 = new Fragment2();
            fragment2.setChangeFragmentListener(this);

            initListeners();
        }

    void changeToFrag1() {
            fragmentTransaction = getFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.activity_main_fragment_container,fragment1, "");
            fragmentTransaction.commit();
        }

        void changeToFrag2() {
            fragmentTransaction = getFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.activity_main_fragment_container, fragment2, "");
            fragmentTransaction.commit();
        }

@Override
    public void onChangeFragmentLicked(int fragment) {
        switch (fragment){
            case 1:
                changeToFrag1();
                break;

            case 2:
                changeToFrag2();
                break;
        }
    }

3) Create object from the interface to handle the callback:

public class Fragment1 extends Fragment {

   private ChangeFragmentListener changeFragmentListener;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view =  inflater.inflate(R.layout.fragment_fragment1, container, false);

        view.findViewById(R.id.fragment1_textView).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                changeFragmentListener.onChangeFragmentLicked(2);
            }
        });

        return view;
    }

    public Fragment1 setChangeFragmentListener(ChangeFragmentListener changeFragmentListener) {
        this.changeFragmentListener = changeFragmentListener;
        return this;
    }
}