如何从 recyclerview 片段传递到另一个 recyclerview 片段

Question

有人可以帮助我了解如何将数据从一个 recyclerview 片段传输到另一个 recyclerview 片段吗？

这是我从片段中为我的购物车回收视图新创建的CartRecyclerAdapter.kt。 SubmitItem() 的主要思想是在 Itemrecyclerview 中接受所选项目。

package com.example.karawapplication
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.ImageView
import android.widget.TextView
import android.widget.Toast
import androidx.recyclerview.widget.RecyclerView
import com.bumptech.glide.Glide
import com.bumptech.glide.request.RequestOptions
import com.example.karawapplication.models.ItemPost
import kotlinx.android.synthetic.main.layout_item_cart_list.view.*
import kotlinx.android.synthetic.main.layout_item_list_item.view.*

class CartRecyclerAdapter : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
    private var Items : List<ItemPost> = emptyList()
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
        return ItemRecyclerAdapter.ItemViewHolder(
            LayoutInflater.from(parent.context)
                .inflate(R.layout.layout_item_cart_list, parent, false)
        )
    }

    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
        when(holder)
        {
            is ItemRecyclerAdapter.ItemViewHolder ->
            {
                holder.bind(Items.get(position))
            }
        }
    }

    override fun getItemCount(): Int {
        return Items.size
    }
    fun SubmitItem(Item : ItemPost)
    {
        Items.toMutableList().add(Item)
    }
    class ItemViewHolder constructor(
        Itemview : View
    ): RecyclerView.ViewHolder(Itemview)
    {
        val ItemImage : ImageView = Itemview.Item_image_cart
        val ItemTitle : TextView = Itemview.Item_title_cart
        val ItemCategory: TextView = Itemview.Item_category_cart
        val ItemPrice : TextView = Itemview.Item_price_cart
        fun bind (itempost : ItemPost)
        {
            ItemTitle.setText(itempost.Itemtitle)
            ItemCategory.setText(itempost.ItemCategory)
            ItemPrice.setText(itempost.ItemPrice)
            val requestOptions = RequestOptions()
                .placeholder(R.drawable.ic_baseline_brush_24)
                .error(R.drawable.ic_baseline_brush_24)

            Glide.with(itemView.getContext())
                .applyDefaultRequestOptions(requestOptions)
                .load(itempost.image)
                .into(ItemImage)
        }

    }
}

这是我在我的 ItemRecyclerAdapter.kt 中使用 SubmitItem() 的地方，它包含我的商店应用程序的项目并从另一个片段显示。 CartAdapter 是我最近为了访问函数 SubmitItem().

而创建的购物车适配器

        ItemButton.setOnClickListener()
        {
            Toast.makeText(itemView.context, "${itempost.image}, ${itempost.Itemtitle}, ${itempost.ItemPrice}", Toast.LENGTH_SHORT).show()
            CartAdapter.SubmitItem(ItemPost(itempost.image,itempost.Itemtitle,itempost.ItemCategory,itempost.ItemPrice))
        }

这是我的片段代码

ShopFragment.kt 包含我的物品的回收视图。

package com.example.karawapplication.fragments

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import com.android.volley.Request
import com.android.volley.VolleyError
import com.android.volley.toolbox.JsonArrayRequest
import com.android.volley.toolbox.Volley
import com.example.karawapplication.ItemRecyclerAdapter
import com.example.karawapplication.R
import com.example.karawapplication.models.ItemPost
import kotlinx.android.synthetic.main.fragment_shop.*
import org.json.JSONException
import org.json.JSONObject

// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private const val ARG_PARAM1 = "param1"
private const val ARG_PARAM2 = "param2"

/**
 * A simple [Fragment] subclass.
 * Use the [Shop.newInstance] factory method to
 * create an instance of this fragment.
 */
class Shop : Fragment(){
    // TODO: Rename and change types of parameters
    private lateinit var ItemAdapter : ItemRecyclerAdapter
    private var param1: String? = null
    private var param2: String? = null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {
            param1 = it.getString(ARG_PARAM1)
            param2 = it.getString(ARG_PARAM2)
        }

    }
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_shop, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        initRecyclerView()
        addDataSet()

    }
    // CUSTOM FUNCTIONS
    private fun addDataSet()
    {
        createDataset {
            list -> ItemAdapter.SubmitList(list)
        }
    }
    private fun initRecyclerView()
    {
        ShopRecycleView.layoutManager = LinearLayoutManager(activity)
        ItemAdapter = ItemRecyclerAdapter()
        ShopRecycleView.adapter = ItemAdapter
        //Toast.makeText(context, "Recycler Trigger", Toast.LENGTH_SHORT).show()
    }
     // https://tutorials.eu/json-parsing-and-how-to-use-gson-in-android/
    // Generates the data for the recycleview
    fun createDataset(onSuccess: (List<ItemPost>) -> Unit){
         val url = "http://api.karawcraftventure.com/item"
         // LIST DATA VARIABLE FOR RECYCLEVIEW
         val list = ArrayList<ItemPost>()
         // VOLLEY API REQUEST
         val Queue = Volley.newRequestQueue(activity)
         val jsonObject = JsonArrayRequest(
             Request.Method.GET,url,null,
             {response ->
                 try
                 {
                     for (i in 0 until response.length())
                     {
                         val item : JSONObject = response.getJSONObject(i)
                         val API_Image : String = item.getString("product_url_image")
                         val API_ItemName : String = item.getString("product_name")
                         val API_Price : String = item.getString("product_price")
                         val API_Category : String = item.getString("product_category")
                         // Toast Notif if data is extracted or not
                         //Toast.makeText(context, "$API_ItemName - $API_Price - $API_Category", Toast.LENGTH_SHORT).show()
                         list.add(ItemPost(API_Image, API_ItemName, API_Category, API_Price))
                     }
                     onSuccess(list)
                 }
                 catch (e: JSONException)
                 {
                     e.printStackTrace()
                 }
             },
             { error: VolleyError? -> Toast.makeText(context, error?.message.toString(), Toast.LENGTH_SHORT).show()

             }
         )
         Queue.add(jsonObject)
    }

    companion object {
        /**
         * Use this factory method to create a new instance of
         * this fragment using the provided parameters.
         *
         * @param param1 Parameter 1.
         * @param param2 Parameter 2.
         * @return A new instance of fragment Shop.
         */
        // TODO: Rename and change types and number of parameters
        @JvmStatic

        fun newInstance(param1: String, param2: String) =
            Shop().apply {
                arguments = Bundle().apply {
                    putString(ARG_PARAM1, param1)
                    putString(ARG_PARAM2, param2)
                }
            }
    }
}

另一方面，

Cart.kt 片段包含我的购物车。

package com.example.karawapplication.fragments

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.karawapplication.CartRecyclerAdapter
import com.example.karawapplication.ItemRecyclerAdapter
import com.example.karawapplication.R
import kotlinx.android.synthetic.main.fragment_cart.*
import kotlinx.android.synthetic.main.fragment_shop.*
import kotlinx.android.synthetic.main.fragment_shop.ShopRecycleView

// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private const val ARG_PARAM1 = "param1"
private const val ARG_PARAM2 = "param2"

/**
 * A simple [Fragment] subclass.
 * Use the [Cart.newInstance] factory method to
 * create an instance of this fragment.
 */
class Cart : Fragment() {
    // TODO: Rename and change types of parameters
    private lateinit var ItemAdapter : CartRecyclerAdapter
    private var param1: String? = null
    private var param2: String? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {
            param1 = it.getString(ARG_PARAM1)
            param2 = it.getString(ARG_PARAM2)
        }
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        initRecyclerView()
    }
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_cart, container, false)
    }
    private fun initRecyclerView()
    {
        Cart_RecyclerView.layoutManager = LinearLayoutManager(activity)
        ItemAdapter = CartRecyclerAdapter()
        Cart_RecyclerView.adapter = ItemAdapter
        //Toast.makeText(context, "Recycler Trigger", Toast.LENGTH_SHORT).show()
    }

    companion object {
        /**
         * Use this factory method to create a new instance of
         * this fragment using the provided parameters.
         *
         * @param param1 Parameter 1.
         * @param param2 Parameter 2.
         * @return A new instance of fragment Cart.
         */
        // TODO: Rename and change types and number of parameters
        @JvmStatic
        fun newInstance(param1: String, param2: String) =
            Cart().apply {
                arguments = Bundle().apply {
                    putString(ARG_PARAM1, param1)
                    putString(ARG_PARAM2, param2)
                }
            }
    }
}

代码没有错误，但在我的购物车回收视图片段中没有显示任何输出。

Answer 1

（我将在这里遵循变量和函数的“以小写字母开头”的约定，因为我累了而且不那么混乱）

您的 submitItem 函数只是创建 items (items.toMutableList()) 的新副本并添加到其中。然后当你退出函数时它会立即被丢弃。

处理数据的所有适配器代码（getItemCount、onBindViewHolder）都引用了 items，因此您需要更新它，并让适配器知道它已更改：

fun submitItem(item: ItemPost) {
    // plus creates a copy, but adds the new item without making the result mutable
    items = items.plus(item)
    // we also need to tell the adapter that the data has changed, so it can
    // update - there are more efficient calls (you'll probably get a lint
    // warning telling you to use one) but this is the simplest
    notifyDataSetChanged()
}

这只是让您的适配器正确更新 - 我假设您已正确设置两个片段之间的通信（通过父 activity 进行通信，将一个片段的适配器传递到另一个片段，使用视图模型）。如果您需要，请阅读此内容：Communicating with fragments

如何从 recyclerview 片段传递到另一个 recyclerview 片段

How to pass from recyclerview fragment to another recyclerview fragment

api

android

android-fragments

kotlin

android-recyclerview