Kotlin：单击 RecycleView 项目时显示 AlertDialog

Question

现在我正在研究在单击 RecyclerView 项目时显示 AlertDialog。 但是，我不知道如何为点击监听器设置适配器。 你能给我一个小费吗？

首先，我尝试将 AlertDialog 放在这个 Main Activity 中。 这是正确的位置吗？

主活动

class MainActivity : AppCompatActivity() {

    private val foodList = listOf(
        FoodModel("Noodle", 2),
        FoodModel("Cake", 3),
        FoodModel("Pizza", 4),
        FoodModel("Stake", 5),
        FoodModel("Chicken", 4)
    )

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


        val adapter = FoodDataAdapter(foodList)
        adapter.notifyDataSetChanged()
        foodListView.adapter = adapter
        foodListView.layoutManager = LinearLayoutManager(this)

        fun onItemClick(item: FoodModel, position: Int) {
            val dialog = AlertDialog.Builder(this)
            dialog.setTitle("Item deletion")
            dialog.setMessage("Do you want to delete this item?")
            dialog.setPositiveButton("Yes", DialogInterface.OnClickListener { _, _ ->
            })
            dialog.setNegativeButton("No", DialogInterface.OnClickListener { _, _ ->
            })
            dialog.setNeutralButton("Cancel", DialogInterface.OnClickListener { _, _ ->
            })
            dialog.show()
        }
    }
}

这是适配器。

class FoodDataAdapter(val list: List<FoodModel>):RecyclerView.Adapter<FoodDataViewHolder>(){
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FoodDataViewHolder {
        val view = LayoutInflater.from(parent.context).inflate(R.layout.item_food,parent,false)
        return FoodDataViewHolder(view)
    }

    override fun getItemCount(): Int {
       return list.count()
    }

    override fun onBindViewHolder(holder: FoodDataViewHolder, position: Int) {
        holder.containerView.nameText.text=list[position].name
        holder.containerView.priceText.text="${list[position].price}dollar"
    }
}

视图支架

class FoodDataViewHolder(override val containerView: View) : RecyclerView.ViewHolder(containerView),LayoutContainer

Answer 1

我编辑了你的代码。主要活动：

class MainActivity : AppCompatActivity(), FoodDataAdapter.OnItemClickListener {

var foodList = ArrayList<FoodModel>()
lateinit var adapter : FoodDataAdapter
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    foodlist.add(FoodModel("Noodle", 2))
    foodlist.add(FoodModel("Cake", 3))
    foodlist.add(FoodModel("Pizza", 4))
    foodlist.add(FoodModel("Stake", 5))
    foodlist.add(FoodModel("Chicken", 4))

    adapter = FoodDataAdapter(foodList, this)
    foodListView.adapter = adapter
    foodListView.layoutManager = LinearLayoutManager(this)

}

override fun alertDialog(position: Int) {
    val dialog = AlertDialog.Builder(this)
    dialog.setTitle("Item deletion")
    dialog.setMessage("Do you want to delete this item?")
    dialog.setPositiveButton("Yes", DialogInterface.OnClickListener { _, _ -> 
    adapter.removeItem(position)
    })
    dialog.setNegativeButton("No", DialogInterface.OnClickListener { _, _ ->
    })
    dialog.setNeutralButton("Cancel", DialogInterface.OnClickListener { _, _ ->
    })
    dialog.show()
}
}

食物数据适配器：

class FoodDataAdapter(var list: ArrayList<FoodModel>, var listener : FoodDataAdapter.OnItemClickListener):RecyclerView.Adapter<FoodDataAdapter.FoodDataViewHolder>(){

interface OnItemClickListener {
    fun alertDialog(position : Int)
}

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FoodDataViewHolder {
    val view = LayoutInflater.from(parent.context).inflate(R.layout.item_food,parent,false)
    return FoodDataViewHolder(view)
}

override fun getItemCount(): Int {
    return list.count()
}

fun removeItem(position: Int) {
    list.removeAt(position)
    notifyItemRemoved(position)
}

override fun onBindViewHolder(holder: FoodDataViewHolder, position: Int) {
    holder.nameText.text=list[position].name
    holder.priceText.text="${list[position].price}dollar"
}

inner class FoodDataViewHolder(containerView: View) : RecyclerView.ViewHolder(containerView),
    View.OnClickListener {

    var nameText: TextView = containerView.findViewById(R.id.nameText)
    var priceText: TextView = containerView.findViewById(R.id.priceText)

    init {
        containerView.setOnClickListener(this)
    }

    override fun onClick(v: View?) {
        listener.alertDialog(adapterPosition)
    }
}
}

Answer 2

我只是像这样在适配器的末尾添加了“removeAt”的声明代码，

class FoodDataAdapter(val list: List<FoodModel>,var itemClicklistener : OnItemClickListener):RecyclerView.Adapter<FoodDataAdapter.FoodDataViewHolder>() {

    interface OnItemClickListener {
        fun onItemClick(position: Int)
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FoodDataViewHolder {
        val view = LayoutInflater.from(parent.context).inflate(R.layout.item_food, parent, false)
        return FoodDataViewHolder(view)
    }

    override fun getItemCount(): Int {
        return list.count()
    }

    fun removeItem(position: Int) {
        list.removeAt(position)
        notifyItemRemoved(position)
    }

    override fun onBindViewHolder(holder: FoodDataViewHolder, position: Int) {
        holder.nameText.text = list[position].name
        holder.priceText.text = "${list[position].price} dollar"
    }

    inner class FoodDataViewHolder(containerView: View) : RecyclerView.ViewHolder(containerView),
        View.OnClickListener {
        var nameText: TextView = containerView.findViewById(R.id.nameText)
        var priceText: TextView = containerView.findViewById(R.id.priceText)

        init {
            containerView.setOnClickListener(this)
        }

        override fun onClick(v: View?) {
            itemClicklistener.onItemClick(adapterPosition)
        }
    }
}

private fun Any.removeAt(position: Int) {

}

并且还像这样更改了主要活动。

class MainActivity : AppCompatActivity(), FoodDataAdapter.OnItemClickListener {

    private val foodList = arrayListOf(
        FoodModel("Noodle", 3),
        FoodModel("Cake", 5),
        FoodModel("Pizza", 7),
        FoodModel("Stake", 8),
        FoodModel("Chicken", 8)
    )
    var adapter: FoodDataAdapter? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        adapter = FoodDataAdapter(foodList, this)
        foodListView.adapter = adapter
        foodListView.layoutManager = LinearLayoutManager(this)
    }

    override fun onItemClick(position: Int) {
        val dialog = AlertDialog.Builder(this)
        dialog.setTitle("Item deletion")
        dialog.setMessage("Do you want to delete this item?")
        dialog.setPositiveButton("Yes", DialogInterface.OnClickListener { _, _ ->
            adapter?.removeItem(position)
        })
        dialog.setNegativeButton("No", DialogInterface.OnClickListener { _, _ ->
        })
        dialog.setNeutralButton("Cancel", DialogInterface.OnClickListener { _, _ ->
        })
        dialog.show()
    }
}

而且它有效！但是……一个问题是…… 删除列表后，最后一个列表保留出现。 列表总数没有减少..

哈哈 又一个“鸡”出现了。你知道怎么解决吗？