在水平线性布局的Recycleview末尾添加按钮(它必须水平滚动，包括按钮

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recyclerView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:scrollbars="horizontal" />

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <!-- 在此添加你的Recycleview项布局 -->

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="按钮" />

</LinearLayout>

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
    // ...

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_layout, parent, false);
        return new ViewHolder(itemView);
    }

    // ...
}

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
    // ...

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        // 绑定数据到Recycleview项

        holder.button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // 处理按钮点击事件
            }
        });
    }

    // ...
}