Item Touch Helper 的空列表不包含索引 0 处的元素

Question

我在使用 ItemTouchHelper 和我的 recyclerview 时遇到了两个问题。我在 Main Activity.

中的不同片段中有两个回收器视图

我的第一个问题是 Item touch helper 不会滑动或无法用于我的第二个回收器视图，即使它们几乎相同。
每当我滑动删除时，我都会得到 Empty list doesn't contain element at index 0。我有点理解为什么，但我看到其他人使用相同的方法，所以我不明白如何解决。

片段1（可滑动）：

    package com.example.bubblereminder

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import androidx.recyclerview.widget.ItemTouchHelper
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.example.bubblereminder.room.RemindersListAdapter
import com.example.bubblereminder.room.RemindersViewModel
import kotlinx.android.synthetic.main.fragment_scheduled.*

class ScheduledFragment : Fragment() {
    private lateinit var reminderViewModel: RemindersViewModel

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {

        val v = inflater.inflate(R.layout.fragment_scheduled, container, false)

        return v
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)

        val recyclerView = view?.findViewById<RecyclerView>(R.id.recycler_scheduled)
        val adapter = context?.let { RemindersListAdapter(it) }
        if (recyclerView != null) {
            recyclerView.adapter = adapter
        }
        if (recyclerView != null) {
            recyclerView.layoutManager = LinearLayoutManager(context)
        }

        this.reminderViewModel = ViewModelProvider(this).get(RemindersViewModel::class.java)
        reminderViewModel.allRemindersDue.observe(viewLifecycleOwner, Observer { reminders ->
            // Update the cached copy of the words in the adapter.
            reminders?.let {
                if (adapter != null) {
                    adapter.setReminders(it)
                }
            }
        })

        ItemTouchHelper(itemTouchHelperCallback).attachToRecyclerView(recycler_scheduled)
    }

    private val itemTouchHelperCallback = object : ItemTouchHelper.SimpleCallback(0,
        ItemTouchHelper.LEFT)
    {
        override fun onMove(
            recyclerView: RecyclerView,
            viewHolder: RecyclerView.ViewHolder,
            target: RecyclerView.ViewHolder
        ): Boolean {
            TODO("Not yet implemented")
        }

        override fun onSwiped(viewHolder: RecyclerView.ViewHolder, position: Int) {
            reminderViewModel.delete(RemindersListAdapter(activity as MainActivity).getReminderAt(viewHolder.adapterPosition))
        }

    }
}

片段2（不能刷）：

    package com.example.bubblereminder

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import androidx.recyclerview.widget.ItemTouchHelper
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.example.bubblereminder.room.RemindersListAdapter
import com.example.bubblereminder.room.RemindersViewModel
import kotlinx.android.synthetic.main.fragment_done.*

class DoneFragment : Fragment() {
    private lateinit var reminderViewModel: RemindersViewModel

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {

        val v = inflater.inflate(R.layout.fragment_scheduled, container, false)

        return v
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)

        val recyclerView = view?.findViewById<RecyclerView>(R.id.recycler_scheduled)
        val adapter = context?.let { RemindersListAdapter(it) }
        if (recyclerView != null) {
            recyclerView.adapter = adapter
        }
        if (recyclerView != null) {
            recyclerView.layoutManager = LinearLayoutManager(context)
        }

        this.reminderViewModel = ViewModelProvider(this).get(RemindersViewModel::class.java)
        reminderViewModel.allRemindersDone.observe(viewLifecycleOwner, Observer { reminders ->
            // Update the cached copy of the words in the adapter.
            reminders?.let {
                if (adapter != null) {
                    adapter.setReminders(it)
                }
            }
        })

        ItemTouchHelper(itemTouchHelperCallback).attachToRecyclerView(recycler_done)
    }

    private val itemTouchHelperCallback = object : ItemTouchHelper.SimpleCallback(0,
        ItemTouchHelper.LEFT)
    {
        override fun onMove(
            recyclerView: RecyclerView,
            viewHolder: RecyclerView.ViewHolder,
            target: RecyclerView.ViewHolder
        ): Boolean {
            TODO("Not yet implemented")
        }

        override fun onSwiped(viewHolder: RecyclerView.ViewHolder, position: Int) {
            reminderViewModel.delete(RemindersListAdapter(activity as MainActivity).getReminderAt(viewHolder.adapterPosition))
        }

    }
}

我的适配器：

    package com.example.bubblereminder.room

import android.content.Context
import android.graphics.Color
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.TextView
import androidx.lifecycle.LiveData
import androidx.recyclerview.widget.RecyclerView
import com.example.bubblereminder.R
import java.util.*

class RemindersListAdapter internal constructor(
    context: Context
) : RecyclerView.Adapter<RemindersListAdapter.RemindersViewHolder>() {

    private val inflater: LayoutInflater = LayoutInflater.from(context)
    private var reminders = emptyList<Reminders>() // Cached copy of words


        inner class RemindersViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        val remindersItemView: TextView = itemView.findViewById(R.id.recycler_item_text)
        val remindersImageView: ImageView = itemView.findViewById(R.id.recycler_item_image)
    }

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

        val itemView = inflater.inflate(R.layout.layout_recycler_item, parent, false)
        return RemindersViewHolder(itemView)
    }

    override fun onBindViewHolder(holder: RemindersViewHolder, position: Int) {
        val current = reminders[position]
        holder.remindersItemView.text = current.reminderText
        if (holder.remindersItemView.getText().toString().contains(taskOne)) {
            holder.remindersItemView.setTextColor(Color.parseColor("#FF00B59C"))
            holder.remindersImageView.setImageResource(R.drawable.ic_washing_machine)
        }
        if (holder.remindersItemView.getText().toString().contains(taskTwo)) {
            holder.remindersItemView.setTextColor(Color.parseColor("#EA5455"))
            holder.remindersImageView.setImageResource(R.drawable.ic_iron)
        }
        if (holder.remindersItemView.getText().toString().contains(taskThree)) {
            holder.remindersImageView.setImageResource(R.drawable.ic_shirt)
            holder.remindersItemView.setTextColor(Color.parseColor("#FFFD5900"))
        }
        if (holder.remindersItemView.getText().toString().contains(taskFour)) {
            holder.remindersImageView.setImageResource(R.drawable.ic_dumbbell)
            holder.remindersItemView.setTextColor(Color.parseColor("#8C1BAB"))
        }
        if (holder.remindersItemView.getText().toString().contains(taskFive)) {
            holder.remindersImageView.setImageResource(R.drawable.ic_bathtub)
            holder.remindersItemView.setTextColor(Color.parseColor("#0396FF"))
        }
    }

    override fun getItemCount() = reminders.size

    internal fun setReminders(reminders: List<Reminders>) {
        this.reminders = reminders
        notifyDataSetChanged()
    }

    private val taskOne = "Camasirlar Yikandi"
    private val taskTwo = "Kiyafetler Utulendi"
    private val taskThree = "Kiyafetler Duruldu"
    private val taskFour = "Egzersiz Yapildi"
    private val taskFive = "Banyo Yapildi"

    fun getReminderAt(position: Int) : Reminders {
       return reminders[position]
    }


}

谢谢你的帮助。

Answer 1

我为第二个片段夸大了错误的视图，这就是为什么它似乎不起作用的原因。

关于尺码问题；由于某种原因更换适配器：

return this.reminders = reminders

至

return reminders = reminders

并在片段中进行更改：

reminderViewModel.delete(RemindersListAdapter(activity as MainActivity).getReminderAt(viewHolder.adapterPosition))

至

val position = viewHolder.adapterPosition val myReminder: Reminders = adapter!!.getReminderAt(position) reminderViewModel.delete(myReminder)

现在工作得很好。

Item Touch Helper 的空列表不包含索引 0 处的元素

Empty list doesn't contain element at index 0 for Item Touch Helper

android-fragments

android-recyclerview

itemtouchhelper

android-room