android - lateinit 属性绑定(bind)尚未初始化

Question

我知道有类似的问题，但我只是找不到类似的东西，我一直在学习新的东西来学习，同时将 kotlin 合成转换为 viewvbinding模式，我遇到了这个错误

kotlin.UninitializedPropertyAccessException: lateinit property binding has not been initialized
        at com.codepalace.chatbot.ui.MessagingAdapter.onBindViewHolder(MessagingAdapter.kt:60)
        at com.codepalace.chatbot.ui.MessagingAdapter.onBindViewHolder(MessagingAdapter.kt:17)

它说我必须初始化绑定(bind)，但我不知道把它放在哪里。
这是代码。

class MessagingAdapter: RecyclerView.Adapter<MessagingAdapter.MessageViewHolder>() {

var messagesList = mutableListOf<Message>()
private lateinit var binding: MessageItemBinding


inner class MessageViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    init {
        itemView.setOnClickListener {

            //Remove message on the item clicked
            messagesList.removeAt(adapterPosition)
            notifyItemRemoved(adapterPosition)
        }
    }
}

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

    return MessageViewHolder(
        LayoutInflater.from(parent.context).inflate(R.layout.message_item, parent, false)
    )
}

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

@SuppressLint("SetTextI18n")
override fun onBindViewHolder(holder: MessageViewHolder, position: Int) {
    val currentMessage = messagesList[position]


    when (currentMessage.id) {
        SEND_ID -> {
            holder.itemView.findViewById<View>(R.id.tv_message).apply {
                binding.tvMessage.text = currentMessage.message
                visibility = View.VISIBLE
            }
            holder.itemView.findViewById<View>(R.id.tv_bot_message).visibility = View.GONE
        }
        RECEIVE_ID -> {
            holder.itemView.findViewById<View>(R.id.tv_bot_message).apply {
                binding.tvBotMessage.text = currentMessage.message
                visibility = View.VISIBLE
            }
            holder.itemView.findViewById<View>(R.id.tv_message).visibility = View.GONE
        }
    }
}

fun insertMessage(message: Message) {
    this.messagesList.add(message)
    notifyItemInserted(messagesList.size)
}

Answer 1

private lateinit var binding: MessageItemBinding

你没有初始化 binding对象，因为您将其定义为lateinit，那么您应该定义它。
这通常在 onCreateViewHolder 中

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): TrackedActivityHolder {
    val inflater = LayoutInflater.from(parent.context)
    binding = DataBindingUtil.inflate<MessageItemBinding>(inflater, R.layout.message_item, parent, false)
    return MessageViewHolder(
        binding
    )
}

更新
您需要接受 MessageItemBinding键入而不是 View在 MessageViewHolder构造函数，并使用 itemView.root获取列表项的 Root View 。

inner class MessageViewHolder(itemView: MessageItemBinding) : RecyclerView.ViewHolder(itemView.root) {
    init {
        itemView.root.setOnClickListener {

            //Remove message on the item clicked
            messagesList.removeAt(adapterPosition)
            notifyItemRemoved(adapterPosition)
        }
    }
}