Kotlin 我目前正在聊天应用程序中实现分页3.0库

这是我用来在两个用户之间显示文本消息而不使用分页的适配器

class ChatAdapter(private val message: List<ChatMessage>) :
RecyclerView.Adapter<RecyclerView.ViewHolder>() {
companion object {
    const val VIEW_TYPE_1 = 1
    const val VIEW_TYPE_2 = 2
}

private inner class View1ViewHolder(itemView: View) :
    RecyclerView.ViewHolder(itemView) {
    val textMessage: TextView = itemView.textMessage
    val messageTimestamp: TextView = itemView.messageTimestamp
    val imageMessage: ImageView = itemView.imageMessage
    val imageCover: ImageView = itemView.imageCover
    val deliveredReceipt: ImageView = itemView.delivered_image
    fun bind(position: Int) {
        setIsRecyclable(false)
        val item = message[position]
        val itemPrev = if (position !== 0) {
            message[position - 1]
        } else message[position]

        if(item.status){
            deliveredReceipt.visibility = View.VISIBLE
        }

        if (item.url == "") {
            textMessage.text = item.text
            if (convertDurationToFormatted(
                    itemPrev.timestamp * 1000,
                    item.timestamp * 1000
                ) || itemPrev == message[position]
            ) {
                messageTimestamp.visibility = View.VISIBLE
                messageTimestamp.text = getDateTime(item.timestamp)
            } else {
                messageTimestamp.visibility = View.GONE
            }

        } else if (item.url !== "") {
            textMessage.visibility = View.GONE
            messageTimestamp.visibility = View.GONE
            Picasso.get().load(item.url).into(imageMessage)
            imageCover.visibility = View.VISIBLE
            imageMessage.visibility = View.VISIBLE
            imageMessage.setOnClickListener {
                val options = arrayOf<CharSequence>(
                    "View Image", "Cancel"
                )

                val builder: AlertDialog.Builder = AlertDialog.Builder(itemView.context)
                builder.setTitle("what now?")
                builder.setItems(options) { _, which ->
                    if (which == 0) {
                        val intent = Intent(builder.context, ViewFullImageActivity::class.java)
                        intent.putExtra("url", item.url)
                        builder.context.startActivity(intent)
                    }
                }
                builder.show()
            }
        }
    }
}

private inner class View2ViewHolder(itemView: View) :
    RecyclerView.ViewHolder(itemView) {
    val textMessage: TextView = itemView.textMessage
    val messageTimestamp: TextView = itemView.messageTimestamp
    val imageMessage: ImageView = itemView.imageMessage
    val imageCover: ImageView = itemView.imageCover
    fun bind(position: Int) {
        setIsRecyclable(false)
        val item = message[position]
        val itemPrev = if (position !== 0) {
            message[position - 1]
        } else message[position]
        if (item.url == "") {
            textMessage.text = item.text
            if (convertDurationToFormatted(
                    itemPrev.timestamp * 1000,
                    item.timestamp * 1000
                ) || itemPrev == message[position]
            ) {
                messageTimestamp.visibility = View.VISIBLE
                messageTimestamp.text = getDateTime(item.timestamp)
            }
        } else if (item.url !== "") {
            textMessage.visibility = View.GONE
            messageTimestamp.visibility = View.GONE
            Picasso.get().load(item.url).into(imageMessage)
            imageCover.visibility = View.VISIBLE
            imageMessage.visibility = View.VISIBLE
            imageMessage.setOnClickListener {
                val options = arrayOf<CharSequence>(
                    "View Image", "Cancel"
                )

                val builder: AlertDialog.Builder = AlertDialog.Builder(itemView.context)
                builder.setTitle("what now?")
                builder.setItems(options) { _, which ->
                    if (which == 0) {
                        val intent = Intent(builder.context, ViewFullImageActivity::class.java)
                        intent.putExtra("url", item.url)
                        builder.context.startActivity(intent)
                    }
                }
                builder.show()
            }
        }
    }
}


override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
    if (viewType == VIEW_TYPE_1) {
        return View1ViewHolder(
            LayoutInflater.from(parent.context).inflate(R.layout.chat_row_to, parent, false)
        )
    }
    return View2ViewHolder(
        LayoutInflater.from(parent.context).inflate(R.layout.chat_row_from, parent, false)
    )
}

override fun getItemCount(): Int = message.size

private fun getDateTime(s: Long): String? {
    return try {
        val sdf = SimpleDateFormat("EEE,hh:mmaa", Locale.getDefault())
        val netDate = Date(s * 1000)
        sdf.format(netDate)
    } catch (e: Exception) {
        e.toString()
    }
}

override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
    if (message[position].fromId == Firebase.auth.uid) {
        (holder as View1ViewHolder).bind(position)
    } else {
        (holder as View2ViewHolder).bind(position)
    }
}

override fun getItemViewType(position: Int): Int {
    return if (message[position].fromId == Firebase.auth.uid) {
        VIEW_TYPE_1
    } else {
        VIEW_TYPE_2
    }
}

class ChatAdapter（专用val消息：列表）：
RecyclerView.Adapter（）{
伴星{
常量值视图类型=1
常量值视图类型2=2
}
私有内部类View1ViewHolder（itemView:View）：
RecyclerView.ViewHolder（itemView）{
val textMessage:TextView=itemView.textMessage
val messageTimestamp:TextView=itemView.messageTimestamp
val imageMessage:ImageView=itemView.imageMessage
val imageCover:ImageView=itemView.imageCover
val deliveredReceipt:ImageView=itemView.delivered\u图像
趣味绑定（位置：Int）{
setIsRecyclable（错误）
val项目=消息[位置]
val itemprov=if（位置！==0）{
信息[位置-1]
}else消息[位置]
如果（项目状态）{
deliveredReceipt.visibility=View.VISIBLE
}
如果（item.url==“”）{
textMessage.text=item.text
如果（转换持续时间到格式）(
itemPrev.timestamp*1000，
item.timestamp*1000
)| | itemprov==消息[位置]
) {
messageTimestamp.visibility=View.visibility
messageTimestamp.text=getDateTime（item.timestamp）
}否则{
messageTimestamp.visibility=View.GONE
}
}else if（item.url！==“”）{
textMessage.visibility=View.GONE
messageTimestamp.visibility=View.GONE
Picasso.get（）.load（item.url）.into（imageMessage）
imageCover.visibility=View.VISIBLE
imageMessage.visibility=View.VISIBLE
imageMessage.setOnClickListener{
val options=arrayOf(
“查看图像”、“取消”
)
val builder:AlertDialog.builder=AlertDialog.builder（itemView.context）
builder.setTitle（“现在怎么办？”）
setItems（选项）{{u0，其中->
if（which==0）{
val intent=intent（builder.context，ViewFullImageActivity:：class.java）
intent.putExtra（“url”，item.url）
builder.context.startActivity（intent）
}
}
builder.show（）
}
}
}
}
私有内部类View2ViewHolder（项目视图：视图）：
RecyclerView.ViewHolder（itemView）{
val textMessage:TextView=itemView.textMessage
val messageTimestamp:TextView=itemView.messageTimestamp
val imageMessage:ImageView=itemView.imageMessage
val imageCover:ImageView=itemView.imageCover
趣味绑定（位置：Int）{
setIsRecyclable（错误）
val项目=消息[位置]
val itemprov=if（位置！==0）{
信息[位置-1]
}else消息[位置]
如果（item.url==“”）{
textMessage.text=item.text
如果（转换持续时间到格式）(
itemPrev.timestamp*1000，
item.timestamp*1000
)| | itemprov==消息[位置]
) {
messageTimestamp.visibility=View.visibility
messageTimestamp.text=getDateTime（item.timestamp）
}
}else if（item.url！==“”）{
textMessage.visibility=View.GONE
messageTimestamp.visibility=View.GONE
Picasso.get（）.load（item.url）.into（imageMessage）
imageCover.visibility=View.VISIBLE
imageMessage.visibility=View.VISIBLE
imageMessage.setOnClickListener{
val options=arrayOf(
“查看图像”、“取消”
)
val builder:AlertDialog.builder=AlertDialog.builder（itemView.context）
builder.setTitle（“现在怎么办？”）
setItems（选项）{{u0，其中->
if（which==0）{
val intent=intent（builder.context，ViewFullImageActivity:：class.java）
intent.putExtra（“url”，item.url）
builder.context.startActivity（intent）
}
}
builder.show（）
}
}
}
}
override fun onCreateViewHolder（父级：ViewGroup，viewType:Int）：RecyclerView.ViewHolder{
如果（视图类型==视图类型1）{
返回视图1视图保持器(
LayoutFlater.from（parent.context）.充气（R.layout.chat\u row\u to，parent，false）
)
}
返回View2ViewHolder(
LayoutFlater.from（parent.context）。充气（R.layout.chat\u row\u from，parent，false）
)
}
重写getItemCount（）：Int=message.size
private fun getDateTime（s:Long）：字符串{
回击{
val sdf=SimpleDataFormat（“EEE，hh:mmaa”，Locale.getDefault（））
val netDate=日期（s*1000）
sdf.format（netDate）
}捕获（e：例外）{
e、 toString（）
}
}
覆盖onBindViewHolder（holder:RecyclerView.ViewHolder，位置：Int）{
if（消息[position].fromId==Firebase.auth.uid）{
（支架为View1ViewHolder）。绑定（位置）
}否则{
（支架为View2ViewHolder）。绑定（位置）
}
}
覆盖getItemViewType（位置：Int）：Int{
返回if（消息[position].fromId==Firebase.auth.uid）{
视图类型1
}否则{
视图类型2
}
}

}

现在我必须转到分页数据适配器。 如何像在上面的适配器中那样在其中使用多种视图类型

在示例适配器下面附加扩展分页数据适配器

class UserAdapter(diffCallback: DiffUtil.ItemCallback<User>) :
  PagingDataAdapter<User, UserViewHolder>(diffCallback) {
  override fun onCreateViewHolder(
    parent: ViewGroup,
    viewType: Int
  ): UserViewHolder {
    return UserViewHolder(parent)
  }

  override fun onBindViewHolder(holder: UserViewHolder, position: Int) {
    val item = getItem(position)
    // Note that item may be null. ViewHolder must support binding a
    // null item as a placeholder.
    holder.bind(item)
  }
}

类UserAdapter（diffCallback:DiffUtil.ItemCallback）： PagingDataAdapter（diffCallback）{ 覆盖视图保持器( 父对象：视图组， 视图类型：Int )：UserViewHolde