通过在 recycleradapter 中实现接口，使用 kotlin 通过回收器适配器将哈希映射写入 Firebase

Question

I want to write a hashmap into my firebase using the click listener which I have implemented in the fragment which acts only if one of the items is selected. but I get an error that I haven't got anytime before.

The logcat shows:

java.lang.IndexOutOfBoundsException: Index: 2, Size: 2
        at java.util.ArrayList.get(ArrayList.java:437)
        at com.reazon.foodrunner.adapter.MenuRecyclerAdapter$MenuViewHolder$bind$1$1.onDataChange(MenuRecyclerAdapter.kt:104)
        at com.google.firebase.database.core.ValueEventRegistration.fireEvent(ValueEventRegistration.java:75)
        at com.google.firebase.database.core.view.DataEvent.fire(DataEvent.java:63)
        at com.google.firebase.database.core.view.EventRaiser$1.run(EventRaiser.java:55)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)

this is my adapter :

package com.reazon.foodrunner.adapter

import android.content.Context
import android.content.Intent
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.RelativeLayout
import android.widget.TextView
import android.widget.Toast
import androidx.recyclerview.widget.RecyclerView
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.database.*
import com.reazon.foodrunner.R
import com.reazon.foodrunner.fragment.CartFragment
import com.reazon.foodrunner.model.MenuItem


class MenuRecyclerAdapter(
    val context: Context,
    private val btnProceedToCart: Button,
    private val proceedToCartPassed: RelativeLayout,
    private val menuList: List<MenuItem>,
    private val listener: ContentListener
) : RecyclerView.Adapter<MenuRecyclerAdapter.MenuViewHolder>() {

    private var goToCart: Int = 0
    private var itemSelected: Int = 0
    private var itemNumber: Int = 0
    private var itemSelectedId = arrayListOf<String>()
    private var itemSelectedName = arrayListOf<String>()
    lateinit var proceedToCartLayout: RelativeLayout

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

        return MenuViewHolder(view)
    }

    override fun getItemCount(): Int {
        return menuList.size
    }

    override fun onBindViewHolder(holder: MenuViewHolder, position: Int) {
        val menuItemItem = menuList[position]
        holder.menuItemName.text = menuItemItem.item.toString()

        proceedToCartLayout = proceedToCartPassed

        btnProceedToCart.setOnClickListener {
            Toast.makeText(context, "Proceeding To Cart", Toast.LENGTH_SHORT).show()
        }

        holder.btnMenuItem.setOnClickListener {
            if (holder.btnMenuItem.text.toString() == "Remove") {
                itemSelected--
                holder.btnMenuItem.text = "ADD"
                itemSelectedId.remove(holder.btnMenuItem.toString())
                itemSelectedName.remove(holder.menuItemName.toString())
                holder.btnMenuItem.setBackgroundResource(R.drawable.btn_menu_add_background)

            } else {
                itemSelected++
                holder.btnMenuItem.text = "Remove"
                itemSelectedId.add(holder.btnMenuItem.toString())
                itemSelectedName.add(holder.menuItemName.toString())
                holder.btnMenuItem.setBackgroundResource(R.drawable.btn_menu_remove_background)

            }
            if (itemSelected > 0) {
                proceedToCartLayout.visibility = View.VISIBLE
            } else {
                proceedToCartLayout.visibility = View.INVISIBLE
            }

            print("$goToCart")
            holder.btnMenuItem.tag = menuItemItem.id

            itemNumber = position + 1

            Log.d("Restaurant", "" + holder.menuItemName.text)
        }
        holder.btnMenuItem.tag = menuItemItem.id.toString() + ""
        holder.bind(itemSelectedId, itemSelectedName, btnProceedToCart, listener)
    }

    class MenuViewHolder(view: View) : RecyclerView.ViewHolder(view) {
        fun bind(menuSelectedId: List<String>, menuList: List<String>, btnProceedToCart: Button, listener: ContentListener) {
            btnProceedToCart.setOnClickListener {

                val mReference = FirebaseDatabase.getInstance().reference.child("Orders")
                    .child(FirebaseAuth.getInstance().currentUser!!.uid)

                mReference.addValueEventListener(object : ValueEventListener {
                        override fun onDataChange(snapshot: DataSnapshot) {
                            val orderHashMap = HashMap<String, Any>()

                            for (item in 1..menuList.size) {
                                orderHashMap["id"] = menuSelectedId[item]
                                orderHashMap["item"] = menuList[item]
                                orderHashMap["cost"] = 200
                                orderHashMap["placed"] = true
                            }

                            mReference.updateChildren(orderHashMap)
                        }

                        override fun onCancelled(error: DatabaseError) {
                            Log.d("MenuRecyclerAdapter", error.message)

                        }

                    })

                listener.openCart()
            }
        }

        val menuItemName: TextView = view.findViewById(R.id.menuItemName)
        val btnMenuItem: Button = view.findViewById(R.id.btnMenuAdd)
    }

    interface ContentListener {
        fun openCart()
    }
}

this is my menu fragment:

package com.reazon.foodrunner.fragment

import android.os.Bundle
import android.util.Log
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.RelativeLayout
import androidx.core.os.bundleOf
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.google.firebase.database.*
import com.reazon.foodrunner.R
import com.reazon.foodrunner.adapter.MenuRecyclerAdapter
import com.reazon.foodrunner.model.MenuItem
import com.reazon.foodrunner.model.Restaurant
import kotlinx.android.synthetic.main.fragment_menu.*
import kotlinx.android.synthetic.main.recycler_home_single_row.*
import kotlinx.android.synthetic.main.recycler_menu_single_row.*

class MenuFragment : Fragment(),MenuRecyclerAdapter.ContentListener{

    private var menuRecyclerAdapter: MenuRecyclerAdapter? = null
    private lateinit var menuReference: DatabaseReference
    private var recyclerMenu: RecyclerView? = null
    internal var menuItemList: MutableList<MenuItem> = ArrayList()
    private var layoutManager: RecyclerView.LayoutManager? = null
    private lateinit var proceedToCartLayout:RelativeLayout
    private lateinit var btnProceedToCart: Button

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        val view = inflater.inflate(R.layout.fragment_menu, container, false)

        menuReference = FirebaseDatabase.getInstance().reference.child("Menu")
        recyclerMenu = view.findViewById(R.id.recyclerMenu)
        btnProceedToCart = view.findViewById(R.id.btnGoToCart)
        proceedToCartLayout = view.findViewById(R.id.rlProceedToCart)

//        val restaurant = (Restaurant::class.java)


        layoutManager = LinearLayoutManager(activity)
        recyclerMenu!!.layoutManager = layoutManager

        retrieveMenu()

        return view
    }

    private fun retrieveMenu() {
        menuItemList.clear()
        menuReference.addValueEventListener(object : ValueEventListener {
            override fun onCancelled(error: DatabaseError) {
                Log.d("ERROR", "" + error.message)
            }

            override fun onDataChange(snapshot: DataSnapshot) {

                for (p0 in snapshot.children) {
                    val menu = p0.getValue(MenuItem::class.java)

                    menuRecyclerAdapter = MenuRecyclerAdapter(context!!, btnProceedToCart, proceedToCartLayout,menuItemList,this@MenuFragment)//,this@MenuFragment)
                    recyclerMenu!!.adapter = menuRecyclerAdapter


                    if (menu != null) {
                        menuItemList.add(menu)
                    }

                }
            }

        })
    }

    fun onBackPressed() {
        when (this.fragmentManager?.findFragmentById(R.id.frame)) {
            !is HomeFragment -> openHome()
        }

    }
    private fun openHome() {
        val transaction = fragmentManager?.beginTransaction()
        transaction?.replace(R.id.frame, HomeFragment())
        transaction?.commit()
    }

    override fun openCart() {
        val transaction = fragmentManager?.beginTransaction()
        transaction?.replace(R.id.frame, CartFragment())
        transaction?.commit()
    }
}

although I haven't made the cart fragment and recycler properly, this is my cart fragment:

package com.reazon.foodrunner.fragment

import android.content.Intent
import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.database.DatabaseReference
import com.google.firebase.database.FirebaseDatabase
import com.reazon.foodrunner.R
import com.reazon.foodrunner.activity.FinishActivity
import com.reazon.foodrunner.adapter.CartRecyclerAdapter
import com.reazon.foodrunner.model.Order
import kotlinx.android.synthetic.main.fragment_cart.*

class CartFragment : Fragment() {

    lateinit var btnCheckout:Button
    private var recyclerCart:RecyclerView? = null
    private var recyclerAdapter:CartRecyclerAdapter? = null
    private var layoutManager:RecyclerView.LayoutManager? = null
    private var orderList:MutableList<Order> =  ArrayList()
    private var cartDatabaseReference:DatabaseReference? = null

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment

        val view = inflater.inflate(R.layout.fragment_cart, container, false)
        btnCheckout = view.findViewById(R.id.btnCheckout)

        val firebaseUid = FirebaseAuth.getInstance().currentUser!!.uid
        cartDatabaseReference = FirebaseDatabase.getInstance().reference.child("Orders").child(firebaseUid)

        layoutManager =LinearLayoutManager(activity)
        recyclerCart = view.findViewById(R.id.recyclerCart)
        recyclerCart!!.layoutManager = layoutManager

        btnCheckout.setOnClickListener {
            val intent = Intent(activity, FinishActivity::class.java )
            startActivity(intent)
        }

        return view
    }

}

Cart adapter:

package com.reazon.foodrunner.adapter

import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
import com.reazon.foodrunner.R
import com.reazon.foodrunner.model.Order
import kotlinx.android.synthetic.*
import kotlinx.android.synthetic.main.recycler_cart_single_row.view.*
import java.util.function.ToDoubleBiFunction

class CartRecyclerAdapter(
    val context: Context,
    private val orderList:List<Order>
):RecyclerView.Adapter<CartRecyclerAdapter.CartViewHolder>() {
    class CartViewHolder(view: View):RecyclerView.ViewHolder(view){
        val txtItemName:TextView = view.findViewById(R.id.txtItemNameCart)

    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CartViewHolder {
        val view  = LayoutInflater.from(parent.context).inflate(R.layout.recycler_cart_single_row,parent,false)
        return CartViewHolder(view)
    }

    override fun onBindViewHolder(holder: CartViewHolder, position: Int) {
        val order = orderList[position]
        holder.txtItemName.text = order.item
    }

    override fun getItemCount(): Int {
        return orderList.size
    }
}

I am unable to understand what to do here to simply upload the hash map of orders and retrieve them.

Answer 1

it was a simple error as I was using the index (indices) in the wrong manner as it should have been

 for (item in menuList.indices) {
      orderHashMap["id"] = menuSelectedId[item]
      orderHashMap["item"] = menuList[item]
      orderHashMap["cost"] = 200
      orderHashMap["placed"] = true
}

and the list got the correct index of each element thereafter, and hashmap was written to firebase.