Error when adding child view to RecyclerView, how to fix?

Question

Java

I am making a drop down list, here is the code. I assume that the error is related to LayoutInflater but I can not figure out how to do it right

public class CompRVAdapter extends RecyclerView.Adapter<CompRVAdapter.ViewHolder> {
    CardView cardView;

    @NonNull
    @Override
    public CompRVAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.fragment_comp, parent, false);
        View child_view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.fragment_child_1, parent, true);
        return new ViewHolder(view, child_view);
    }

    @Override
    public void onBindViewHolder(@NonNull CompRVAdapter.ViewHolder holder, int position) {

    }

    @Override
    public int getItemCount() {
        return 15;
    }

    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        public ViewHolder(View itemView, View childView) {
            super(itemView);
            cardView = (CardView) itemView.findViewById(R.id.cv1);
            CardView childCardView = (CardView) childView.findViewById(R.id.child_cv);
            LinearLayout linearLayout_childItems = (LinearLayout) itemView.findViewById(R.id.child_linear_layout);

            for (int indexView = 0; indexView < 3; indexView++) {
                LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
                linearLayout_childItems.addView(childCardView, layoutParams);
            }
        }

        @Override
        public void onClick(View view) {

        }
    }
}

Here is the text of the error

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:4417)
        at android.view.ViewGroup.addView(ViewGroup.java:4258)
        at android.view.ViewGroup.addView(ViewGroup.java:4230)
        at ru.human_factors.characterist.adapters.CompRVAdapter$ViewHolder.<init>(CompRVAdapter.java:44)
        at ru.human_factors.characterist.adapters.CompRVAdapter.onCreateViewHolder(CompRVAdapter.java:22)
        at ru.human_factors.characterist.adapters.CompRVAdapter.onCreateViewHolder(CompRVAdapter.java:13)
        at android.support.v7.widget.RecyclerView$Adapter.createViewHolder(RecyclerView.java:6685)
        at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5869)
        at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5752)
        at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5748)
        at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2232)
        at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1559)
        at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1519)
        at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:614)
        at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3812)
        at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3529)
        at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:4082)
        at android.view.View.layout(View.java:17637)

Answer 1

inflate(R.layout.fragment_comp, parent, false);

inflate(R.layout.fragment_comp, null);

Answer 2

What kind of obscurantism is going on in the constructor of the holder? In the cycle, the same View is added, of course it will fall. You don't have to do this, do it all in the markup at once.