如何根据所选项目更改 RecyclerView 下面的信息？

Question

I'm making a recycler view with a linear layout horizontal, it looks like this: HorizontalRecyclerView

As you can see under it there are two text view that I want to fill with the item info when the user press an item. I've do two Adapters to show a menu before, this way when you make a long click the item change its layout, but it doesn´t change the information below. The way of manage a selected item usually is using the adapter like this:

if (holder instanceof AdaptadorProyectosViewHolder) {
        ((AdaptadorProyectosViewHolder) holder).tv_nombreProyecto.setText(nombreProyecto.toString());
        ((AdaptadorProyectosViewHolder) holder).tv_nombreClienteProyecto.setText("UN CLIENTE");

        //When it's a long click the menu is shown in the place of the item
        ((AdaptadorProyectosViewHolder) holder).itemView.setOnLongClickListener(new View.OnLongClickListener() {
            @Override
            public boolean onLongClick(View v) {
                mostrarMenu(position); //showMenu(position)
                return true;
            }
        });

What this do is that the layout of an item change (displaying more information, options,etc), but i want the info to be below the Recycler View, not inside it into an item. There's any way to do it?

Here's the xml of the fragment that contains the Recycler View:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".Vistas.Proyectos">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_proyectos"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <TextView
            android:id="@+id/textView3"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="TextView" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="TextView" />
    </LinearLayout>
</LinearLayout>

Answer 1

Relying on little details from your question, here's a quick solution. Add an onClickListener to your adapter:

public interface OnItemClickListener {
        void onItemClick(int position);
    }

Declare the listener's variable and add it to the adapter's constructor:

private final OnItemClickListener listener;
public MyAdapter ( List<Item> items , Context context , OnItemClickListener listener ) {
        mItems = items;
        mContext = context;
        this.listener = listener;
    }
    

Inside ViewHolder, add OnClickListener:

public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener
    {

        private TextView txt;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            
            itemView.setOnClickListener(this);
            txt = itemView.findViewById(R.id.tvItemTitle);
        }
        
        @Override
        public void onClick(View v)
        {
            listener.onItemClick(getAdapterPosition());
        }

    }

After adding these to the adapter, now move to the activity or fragment hosting the recyclerview and implement the onClickListener you just created. Here, I used a fragment:

public class LibraryFragment extends MainActivityFragment implements MyAdapter.OnItemClickListener

Add the following to the newly implemented method:

@Override
    public void onItemClick(int position)
    {
        mtext.setText(mItems.get(position).getName());
    }

All done. Notice that mItems is your list of items, and mtext is the TextView hosting the results, Also, note the getName() method is a method I created. Replace mItems, mtext and getName with your own codes: Extra note: you need to add the listener to the adapter in the fragment:

adapter = new MyAdapter( mItems , getActivity() , this );