数据库处理程序出现问题，应用程序崩溃(kotlin)

我正在创建一个应用程序，该应用程序允许将项目添加到片段内的列表中。现在，每当编译器调用数据库处理程序的函数应用程序崩溃时，我都找不到原因。shopping_list.kt

package com.example.pricetag.fragments
import android.app.AlertDialog
import android.content.Context
import android.content.DialogInterface
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.EditText
import android.widget.TextView
import androidx.fragment.app.Fragment
import androidx.recyclerview.widget.RecyclerView
import com.example.pricetag.R
import com.example.pricetag.fragments.DTO.ItemList
import kotlinx.android.synthetic.main.fragment_shopping_list.*
class shopping_list : Fragment() {
lateinit var dbHandler: DBHandler
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
var view = inflater.inflate(R.layout.fragment_shopping_list, container, false)
val addItem_button = view.findViewById<com.google.android.material.floatingactionbutton.FloatingActionButton>(R.id.fab_shoppiglist)
addItem_button.setOnClickListener {
val dialog = AlertDialog.Builder(getContext())
val tempView = layoutInflater.inflate(R.layout.dialog_shoppinglist,null)
val text_result = tempView.findViewById<EditText>(R.id.et_Itemlist)
dialog.setView(tempView)
dialog.setPositiveButton("Add") { _: DialogInterface, _: Int ->
if (text_result.text.isNotEmpty()) {
val itemList = ItemList()
itemList.name = text_result.text.toString()
dbHandler.addItem(itemList)
}
}
dialog.setNegativeButton("Cancel"){ _: DialogInterface, _: Int->
}
dialog.show()
}
return view
}
private fun refreshList(){
rv_shoppinglist.adapter = ShoppinglistAdpter(this.requireContext(),dbHandler.getItem())
}

class ShoppinglistAdpter(val context: Context, val list: MutableList<ItemList>): RecyclerView.Adapter<ShoppinglistAdpter.ViewHolder>(){
class ViewHolder(v : View) : RecyclerView.ViewHolder(v){
val itemName : TextView = v.findViewById(R.id.tv_item_name)
}
override fun onCreateViewHolder(p0: ViewGroup, pl: Int): ViewHolder {
return ViewHolder(LayoutInflater.from(context).inflate(R.layout.rv_child_shoppinglist,p0))
}
override fun getItemCount(): Int {
return list.size
}
override fun onBindViewHolder(holder: ViewHolder, p1: Int) {
holder.itemName.text = list[p1].name
}
}
}

DBHandler.kt

package com.example.pricetag.fragments
import android.content.ContentValues
import android.content.Context
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteOpenHelper
import android.util.Log
import com.example.pricetag.fragments.DTO.ItemList
class DBHandler(val context: Context) : SQLiteOpenHelper(context, DB_NAME,null, DB_VERSION){
override fun onCreate(db: SQLiteDatabase){
val createItemTable = "CREATE TABLE $TABLE_ITEMS (" +
"$COL_ID integer PRIMARY KEY AUTOINCREMENT," +
"$COL_NAME varchar," +
"$COL_AMOUNT integer);"
db.execSQL(createItemTable)
}
override fun onUpgrade(p0: SQLiteDatabase?, p1: Int, p2: Int) {
}
fun addItem(itemList : ItemList) : Boolean {
Log.i("Err","#9")
val db = writableDatabase
val cv = ContentValues()
cv.put(COL_NAME, itemList.name)
val result = db.insert(TABLE_ITEMS, null, cv)
return result != (-1).toLong()
}
fun getItem() : MutableList<ItemList>{
val result : MutableList<ItemList> = ArrayList()
val db : SQLiteDatabase = readableDatabase
val queryResult = db.rawQuery("SELECT * from $TABLE_ITEMS", null)
if(queryResult.moveToFirst()){
do{
val itemList = ItemList()
itemList.id = queryResult.getLong(queryResult.getColumnIndex(COL_ID))
itemList.name = queryResult.getString(queryResult.getColumnIndex(COL_NAME))
itemList.amount = queryResult.getInt(queryResult.getColumnIndex(COL_AMOUNT))
result.add(itemList)
} while(queryResult.moveToNext())
}
return result
}
}

项目列表.kt

package com.example.pricetag.fragments.DTO
class ItemList {
var id: Long = -1
var name: String = ""
var amount = 0

}

Const.kt

package com.example.pricetag.fragments
const val DB_NAME = "ItemList"
const val DB_VERSION = 1
const val TABLE_ITEMS = "Items"
const val COL_ID = "id"
const val COL_NAME = "name"
const val COL_AMOUNT = "amount"

请帮我找出问题并解决问题。谢谢。祝你今天愉快

编辑：这是压缩日志(错误

2020-08-28 03:42:23.932 6619-6619/com.example.pricetag E/RecyclerView: No adapter attached; skipping layout
2020-08-28 03:42:26.710 6619-6619/com.example.pricetag E/RecyclerView: No adapter attached; skipping layout
2020-08-28 03:42:26.740 6619-6619/com.example.pricetag E/RecyclerView: No adapter attached; skipping layout
2020-08-28 03:42:30.059 6619-6619/com.example.pricetag E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.pricetag, PID: 6619
kotlin.UninitializedPropertyAccessException: lateinit property dbHandler has not been initialized
at com.example.pricetag.fragments.shopping_list.getDbHandler(shopping_list.kt:20)
at com.example.pricetag.fragments.shopping_list$onCreateView$1$1.onClick(shopping_list.kt:38)
at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6710)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:770)

这是压缩日志(调试(：

2020-08-28 03:42:30.059 6619-6619/com.example.pricetag E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.pricetag, PID: 6619
kotlin.UninitializedPropertyAccessException: lateinit property dbHandler has not been initialized
at com.example.pricetag.fragments.shopping_list.getDbHandler(shopping_list.kt:20)
at com.example.pricetag.fragments.shopping_list$onCreateView$1$1.onClick(shopping_list.kt:38)
at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:166)
at android.os.Handler.dispatchMessage(Handler.java:105)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6710)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:770)