带有 kotlin MVVM 和数据绑定的 recyclerview 中的单选按钮

Question

recyclerview 中带有 kotlin、dagger2、retrofit、livedata、MVVM 和数据绑定的 Redio 按钮，我需要从 videModel 更新列表并设置选定位置以找到它 被选中，而其他 on 被取消选中。请建议如何在列表中的 RadioButton 中仅选择一个。 这是我的适配器：-

class DocTypeListAdapter : RecyclerView.Adapter<DocTypeListAdapter.ViewHolder>() {
    private lateinit var postList: List<DriverType>

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

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

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

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

    class ViewHolder(private val binding: ItemDocumentTypeBinding) : RecyclerView.ViewHolder(binding.root) {
        private val viewModel = DocTypeListViewModel()

        fun bind(post: DriverType, position: Int, selectedPosition: Int) {
//            viewModel.bind(post,true)
            viewModel.bind(post,position,selectedPosition)

//             mRadioButton : RadioButton = binding.radioButton;



            viewModel.readioButtonClicked(getAdapterPosition(),position)
            binding.viewModel = viewModel
        }
    }
}

viewModel 喜欢：-

class DocTypeListViewModel : BaseViewModel() {
    private val postTitle = MutableLiveData<String>()
    private val postBody = MutableLiveData<String>()
     val isChecked = MutableLiveData<Boolean>()
    private var mSelectedItem = -1


    fun bind(post: DriverType, position: Int, selectedPosition: Int) {
        postTitle.value = post.driver_type
        postBody.value = post.description

        if ((selectedPosition == -1 && position == 0))
            isChecked.value = true
        else
            if (selectedPosition == position)
                isChecked.value = true
            else
                isChecked.value = false

    }

    fun getPostTitle(): MutableLiveData<String> {
        return postTitle
    }

    fun getPostBody(): MutableLiveData<String> {
        return postBody
    }

    fun getIsChecked(): MutableLiveData<Boolean> {
        return isChecked
    }

    fun readioButtonClicked(selectedPosition: Int, pos:Int) {
        mSelectedItem = selectedPosition

        //            mSelectedItem=getAdapterPosition()
//            notifyDataSetChanged()

    }
}

我的布局：-

<android.support.v7.widget.RecyclerView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                app:adapter="@{viewModel.getDocTypeListAdapter()}"

                android:layout_marginTop="8dp"
                app:layout_constraintTop_toBottomOf="@+id/textView9"
                app:layout_constraintStart_toStartOf="parent"
                android:layout_marginStart="8dp"
                app:layout_constraintEnd_toEndOf="parent"
                android:layout_marginEnd="8dp"
                android:id="@+id/recyclerView"
                android:layout_marginBottom="8dp"
                app:layout_constraintBottom_toTopOf="@+id/button"/>

绑定适配器：-

@BindingAdapter("adapter")
fun setAdapter(view: RecyclerView, adapter: RecyclerView.Adapter<*>) {
    view.adapter = adapter
}

Answer 1

我通常这样做：

class YourAdapter(val selected : (YourClassType) -> Unit) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {

    // override fun onCreateViewHolder

    // override fun getItemCount()

    // override fun onBindViewHolder

    inner class YourViewHolder(val binding: YourClassItemBinding) : RecyclerView.ViewHolder(binding.root) {
        fun setData(item : YourItem) {
            binding.radioButton.setOnClickListener {
                binding.radioButton.checked = true
                selected.invoke(item) // use this if you need the item in your activity
            }
            // binding.viewModel.setData
        }
    }

}

但您可能需要创建自己的函数来取消选中列表中的其他单选按钮项目。

编辑

我认为将适配器放在 xml 文件中不是一个好习惯。

我通常在“拥有” RecyclerView 的活动中这样做：

class YourActivity : AppCompatActivity() {

    var listRv : RecyclerView? = null

    var viewModel = YourViewModel()

    var adapter = YourAdapter {
        // Put here the actions you want to achieve when a user click on an item and the adapter selected val is "invoked"
    }

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

        val binding = DataBindingUtil.setContentView<ActivityYourBinding>(this, R.layout.activity_your_layout)
        binding.viewModel = viewModel

        listRv = binding.yourListId
        listRv?.adapter = adapter // Set your list adapter here
        listRv?.layoutManager = LinearLayoutManager(this)


        // etc.
    }
}

Answer 2

如果您使用 rxjava/rxkotlin 那么 map operator 将帮助您实现上述目标

val item=YourModel()   
val observable:Observable<YourModel>
observable=Observable.fromIterable(list)
observable.map { model->
    model.isChecked = filter.modelType===item.modelType
    }
}.toList().subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread()).subscribe()

map操作使用更新列表后，会产生你想要的结果。