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

Question

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

CartRecyclerAdapter.kt这是我从片段中为我的购物车 recyclerview新创建的。的主要思想SubmitItem()是在Itemrecyclerview中接受选中的项目。

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)
        }

    }
}

这是我在其中使用的地方SubmitItem()，ItemRecyclerAdapter.kt其中包含我的商店应用程序的项目并从另一个片段中显示。CartAdapter 是我最近创建的用于访问该功能的购物车适配器SubmitItem()。

        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recyclerview。

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)
                }
            }
    }
}

Cart.kt另一方面，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)
                }
            }
    }
}

该代码没有错误，但在我的购物车 recyclerview 片段中没有显示任何输出。

标签： androidapikotlinandroid-fragmentsandroid-recyclerview

Answer 1

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

您的submitItem函数只是创建items( items.toMutableList()) 的新副本并添加到该副本。然后，当您退出该功能时，它会立即被丢弃。

所有处理数据（getItemCount, onBindViewHolder）引用的适配器代码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()
}

这只是使您的适配器正确更新-我假设您已正确设置了两个片段之间的通信（通过父活动进行通信，使用视图模型将一个片段的适配器传递给另一个片段）。如果需要，请阅读此内容：与片段通信