android - null 不能转换为非 null 类型 kotlin.collections.List - kotlin

Question

我正在尝试在 RecyclerView 中添加搜索 Filterable。但应用程序因以下错误而崩溃:

kotlin.TypeCastException: null cannot be cast to non-null type kotlin.collections.List at com.kabelash.movies.ui.PostListAdapter$searchFilter$1.publishResults(PostListAdapter.kt:87) at android.widget.Filter$ResultsHandler.handleMessage(Filter.java:284) at android.os.Handler.dispatchMessage(Handler.java:107) at android.os.Looper.loop(Looper.java:214)

适配器:

class PostListAdapter: RecyclerView.Adapter<PostListAdapter.ViewHolder>(), Filterable {
    private lateinit var postListFiltered:List<Data>
    private lateinit var postListFull:List<Data>

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val binding: ListItemBinding = DataBindingUtil.inflate(LayoutInflater.from(parent.context), R.layout.list_item, parent, false)
        return ViewHolder(binding)
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.bind(postListFiltered[position])
    }

    override fun getItemCount(): Int {
        return if(::postListFiltered.isInitialized) postListFiltered.size else 0
    }

    fun updatePostList(postList:List<Data>){
        this.postListFiltered = postList
        notifyDataSetChanged()
    }

    class ViewHolder(private val binding: ListItemBinding): RecyclerView.ViewHolder(binding.root){
        private val viewModel = MoviesViewModel()

        fun bind(post:Data){
            viewModel.bind(post)
            binding.viewModel = viewModel
        }

    }

    override fun getFilter(): Filter? {
        return searchFilter
    }

    private val searchFilter: Filter = object : Filter() {
        override fun performFiltering(constraint: CharSequence?): FilterResults? {
            val filteredList: MutableList<Data> = ArrayList()
            if (constraint == null || constraint.isEmpty()) {
                filteredList.addAll(postListFull)
            } else {
                val filterPattern = constraint.toString().toLowerCase().trim()
                for (item in postListFull) {
                    if (item.title.toLowerCase().contains(filterPattern) || item.genre.toLowerCase().contains(filterPattern)) {
                        filteredList.add(item)
                    }
                }

            }
            val results = FilterResults()
            results.values = filteredList
            return results
        }

        override fun publishResults(constraint: CharSequence?,results: FilterResults) {
            postListFiltered = (results.values as List<Data>)
            notifyDataSetChanged()
        }
    }
}

如果您需要任何其他类文件，请告诉我。有人可以帮我解决吗？

Answer 1

就是这一行: results.values as List<Data>

results.values为空，而您告诉它是一个非空列表，它不能这样做。