Question

代码B是带有RecyclerView.Adapter的自定义RadioButton。

我希望得到RadioButton的当前所选索引，因此我在代码A中添加了一个属性mySelectedIndex，但mySelectedIndex在调用之后不会更改第一次。

我该怎么做？谢谢！

还有更多，

private lateinit var selectedIndex= mCustomAdapter.getSelectedIndex() will not work too!

代码A

private lateinit var mCustomAdapter: CustomAdapter

private val mySelectedIndex by lazy {
        mCustomAdapter.getSelectedIndex()
}


private fun a(){
  backup(mySelectedIndex)
}


private fun b(){
  restore(mySelectedIndex) 
}

代码B

class CustomAdapter (val backupItemList: List<MSetting>) : RecyclerView.Adapter<CustomAdapter.ViewHolder>() {

    val noRecord=-1
    private var mSelectedIndex = noRecord

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CustomAdapter.ViewHolder {
        val v = LayoutInflater.from(parent.context).inflate(R.layout.item_recyclerview, parent, false)
        return ViewHolder(v)
    }

    fun getSelectedIndex():Int{
        return  mSelectedIndex
    }

    fun setSelectedIndex(index:Int){
        if (index in 0..(backupItemList.size-1) ){
            mSelectedIndex=index
        }
        notifyDataSetChanged();
    }

    override fun onBindViewHolder(holder: CustomAdapter.ViewHolder, position: Int) {
        holder.bindItems(backupItemList[position])
    }

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

    inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {

        fun bindItems(aMSetting: MSetting) {          

            itemView.radioButton.setOnClickListener {
                mSelectedIndex=adapterPosition
                notifyDataSetChanged();
            }

            if(adapterPosition == 0 && mSelectedIndex == noRecord) {            
                itemView.radioButton.isChecked = true
                mSelectedIndex=adapterPosition
            }
            else {
                itemView.radioButton.isChecked =(adapterPosition == mSelectedIndex)
            }
        }

    }

}

Answer 1

在此处使用mySelectedIndex委派，您确保在private val mySelectedIndex get () = mCustomAdapter.getSelectedIndex()首次初始化后返回相同的值。

您可能希望省略委派并执行类似的操作：

private val mySelectedIndex
    get () = {
        mCustomAdapter.getSelectedIndex()
    }

作为旁注，上面的代码段不等于以下内容：

getSelectedIndex()

后者将返回Add-TextBox的函数引用，而前者将返回其结果。

Answer 2

替换

Balance

与

.value

或

private val mySelectedIndex by lazy {
    mCustomAdapter.getSelectedIndex()
}

应该有用。

如何在Kotlin中定义返回RadioButton当前值的属性？

2 个答案: