android - 为什么最大长度过滤器不起作用？安卓

Question

当我按下一个按钮时，我会有一个按钮，数量(我产品的数量)将增加一。
并为此值设置一个最大长度。
但是我的代码没有过滤金额。
这是我的适配器:

class RecyclerAdapterMain(


    val product: List<Roomtable>,
    val context: Context


) :
    RecyclerView.Adapter<RecyclerAdapterMain.ViewHolder>() {


    val viewModel: ViewModelRoom by lazy {

        ViewModelProvider.AndroidViewModelFactory(Application()).create(ViewModelRoom::class.java)

    }


    inner class ViewHolder(itemview: View) :
        RecyclerView.ViewHolder(itemview) {


        val title: TextView = itemview.product_txt

        val price: TextView = itemview.price_product

        val imageproduct: ImageView = itemview.product_image

        val btn_add_product: Button = itemview.btn_add_product

        var amount_value: TextView = itemview.amount_value

        val button_remove_product: Button = itemview.button_remove_product



    }


    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {


        val layoutview =
            LayoutInflater.from(parent.context).inflate(R.layout.product_items, parent, false)
        return ViewHolder(layoutview)

    }

    override fun getItemCount(): Int = product.size


    override fun onBindViewHolder(holder: ViewHolder, position: Int) {


        val products = product[position]


        holder.title.text = products.title

        holder.price.text = products.price

        Picasso.get().load(products.image).into(holder.imageproduct)

        holder.amount_value.text = products.amount.toString()


        val anim: Animation =
            AnimationUtils.loadAnimation(this.context, R.anim.anim_for_btn_zoom_out)


        holder.btn_add_product.setOnClickListener {

// this will start an animation on addButton
            it.startAnimation(anim)

            holder.button_remove_product.visibility = View.VISIBLE


            holder.amount_value.visibility = View.VISIBLE

            products.amount++.toString()

            holder.amount_value.text = products.amount.toString()

// this is lengthmax filter but dosen't work

            holder.amount_value.filters = arrayOf(LengthFilter(5))


// this is insert the selected product into roomdatabase

            viewModel.insertItemToCart(
                CartTable(
                    null,
                    products.title,
                    products.price,
                    products.image,
                    products.amount
                )
            )

        }

如何正确过滤我的数量号码？
我的代码有什么问题？
先谢谢了 。

Answer 1

您需要做的是在onClick之后通知RecyclerView有关更改。您可以使用notifyDatasetChanged()做到这一点。如果使用数据类定义“产品”，则可以使用复制机制:

override fun onBindViewHolder(holder: ViewHolder, position: Int) {


        val products = product[position]


        holder.title.text = products.title

        holder.price.text = products.price

        Picasso.get().load(products.image).into(holder.imageproduct)

        holder.amount_value.text = products.amount.toString()


        val anim: Animation =
            AnimationUtils.loadAnimation(this.context, R.anim.anim_for_btn_zoom_out)


        holder.btn_add_product.setOnClickListener {

// this will start an animation on addButton
            it.startAnimation(anim)

            holder.button_remove_product.visibility = View.VISIBLE


            holder.amount_value.visibility = View.VISIBLE

            val changedProducts = products.copy(amount = products.amount++)
            product[holder.adapterPosition] = changedProducts

            holder.amount_value.text = products.amount.toString()

// this is lengthmax filter but dosen't work

            holder.amount_value.filters = arrayOf(LengthFilter(5))


// this is insert the selected product into roomdatabase

            viewModel.insertItemToCart(
                CartTable(
                    null,
                    changedProducts.title,
                    changedProducts.price,
                    changedProducts.image,
                    changedProducts.amount
                )
            )
            notifyDatasetChanged()
    }