我为大学项目创建了一个类似在线购物的应用程序我面临在购物车中实时更新的问题

如何解决我为大学项目创建了一个类似在线购物的应用程序我面临在购物车中实时更新的问题

enter image description here[这是我面临的问题，当我更新产品数量时，价格更新在顶部而不是底部，这是我的代码]

CartItemsAdapter.kt 文件

    class cartItemsAdapter(context: Context,val cartItems: ArrayList<cartDB_offline>) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {

    val context = context

    class ViewHolder(itemView: View): RecyclerView.ViewHolder(itemView){
        fun bind(item: cartDB_offline) {

            val eachItemTotalPrice = item.product_price * item.product_quantity
            itemView.cart_item_name.text = item.product_name
            itemView.cart_item_price.text = eachItemTotalPrice.toString()
            itemView.cart_item_count.text = item.product_quantity.toString()

//            itemView.recyclerview_in_cart.setOnClickListener {
//                val fp =
//            }
        }


    }

    override fun onCreateViewHolder(parent: ViewGroup,viewType: Int): RecyclerView.ViewHolder {
        val view = LayoutInflater.from(parent.context).inflate(R.layout.cart_items,parent,false)


        return ViewHolder(view)

    }

产品的增减

覆盖 fun onBindViewHolder(holder: RecyclerView.ViewHolder,position: Int) { (持有人作为ViewHolder).bind(cartItems[position])

holder.itemView.decrement_in_cart.setOnClickListener {

    val count = holder.itemView.cart_item_count.text.toString().toInt()
    if(count >= 1) {
        val databaseHelper = DatabaseHelper(it.context)
        val item_name = holder.itemView.cart_item_name.text.toString()
        val count_new = databaseHelper.increase_decrease_in_cart("decrement",item_name,count)
        holder.itemView.cart_item_count.text = count_new.toString()

        cartItems[position].product_quantity--
        holder.bind(cartItems[position])

        //PENDING -- Have to refresh price

    }
}

holder.itemView.increment_in_cart.setOnClickListener {

    val count = holder.itemView.cart_item_count.text.toString().toInt()
    if(count < 10)  {
        val databaseHelper = DatabaseHelper(it.context)
        val item_name = holder.itemView.cart_item_name.text.toString()
        val count_new = databaseHelper.increase_decrease_in_cart("increment",count)
        holder.itemView.cart_item_count.text = count_new.toString()

        cartItems[position].product_quantity++
        holder.bind(cartItems[position])

        //PENDING -- Have to refresh price

    }

}

Activity_cart.xml

 <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:background="@color/white"
    android:layout_height="match_parent"
    tools:context=".Cart_Firebase">

    <include layout="@layout/toolbar"/>

    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="65dp"
        android:layout_marginBottom="60dp"
        android:id="@+id/recyclerview_in_cart">

    </androidx.recyclerview.widget.RecyclerView>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:layout_alignParentBottom="true"
        android:weightSum="2">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_margin="4dp"
            android:textSize="20sp"
            android:padding="10dp"
            android:textAlignment="center"
            android:textColor="@color/black"
            android:background="@drawable/input_styles"
            android:id="@+id/total_price_tag"
            android:gravity="center_horizontal" />

        <Button
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:layout_margin="4dp"
            android:onClick="BuyButtonClicked"
            android:id="@+id/buy_button"
            android:textAllCaps="false"
            android:background="@drawable/cart_btn_style"
            android:textSize="20sp"
            android:text="Buy Now"/>
    </LinearLayout>

</RelativeLayout>

its the error the price is updated in top but not in bottom