TabLayout & ViewGroup : The specified child already has a parent. You must call removeView() on the child's parent first

Question

I have a tabLayout setup iwth viewpager on my MainActivity:

tabLayout.setupWithViewPager(viewPager);

The initial fragment loads without any issues. However, when clicking on one of the tab titles I get the following error: "The specified child already has a parent. You must call removeView() on the child's parent first"

here's my fragment setup:

public class ContactsList extends Fragment {

    private static MainActivity mActivity;
    private View view;
    private static Fragment thisFragment;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mActivity = (MainActivity) getActivity();
        thisFragment= this;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View v= inflater.inflate(R.layout.contacts_list_recycler_view, null);
        view=v;
        RecyclerView rv  = (RecyclerView) v.findViewById(R.id.contacts_list_recyclerview);
        setupRecyclerView(rv);
        return rv;
    }

    @Override
    public void onDestroyView() {
        if (view != null) {
             ViewGroup group = (ViewGroup) view.getParent();
            group.removeAllViews();
        }
        super.onDestroyView();
    }

and the viewpager adapter on MainActivity:

static class Adapter extends FragmentPagerAdapter {
    private final List<Fragment> mFragments = new ArrayList<>();
    private final List<String> mFragmentTitles = new ArrayList<>();

    public Adapter(FragmentManager fm) {
        super(fm);
    }

    public void addFragment(Fragment fragment, String title) {
        mFragments.add(fragment);
        mFragmentTitles.add(title);
    }

    @Override
    public Fragment getItem(int position) {
        return mFragments.get(position);
    }

    @Override
    public int getCount() {
        return mFragments.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return mFragmentTitles.get(position);
    }
}

the Logcat has the following:

 java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
        at android.view.ViewGroup.addViewInner(ViewGroup.java:4976)
        at android.view.ViewGroup.addView(ViewGroup.java:4807)

Answer 1

Well, as it turned out after 4h of bug hunting, the error is not on the code but instead on the layout XML files. when loading the fragment, initially i had:

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/contacts_list_recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginBottom="32dp"
        android:scrollbars="vertical"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"></androidx.recyclerview.widget.RecyclerView>


</androidx.constraintlayout.widget.ConstraintLayout>

and as it seems constrainLayout is not allowed and will throw the above error. To solve it, all it was needed, was to remove the constrainLayout from the XML:

<?xml version="1.0" encoding="utf-8"?>
<androidx.recyclerview.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/contacts_list_recyclerview"
android:scrollbars="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent" />

and everything worked as intended.