kotlin 複数のリスト選択ダイアログをコントロール

package com.example.samplelistdialog

open class MySpinnerItem(
    var text: String
)

data class Fruit(
    val id: Int,
    val name: String,
    val limit: String
) : MySpinnerItem(name)

data class MyColor(
    val id: Int,
    var name: String
) : MySpinnerItem(name)

package com.example.samplelistdialog

import android.app.AlertDialog
import android.app.Dialog
import android.content.Context
import android.os.Bundle
import android.widget.ArrayAdapter
import androidx.fragment.app.DialogFragment
import java.lang.IllegalStateException

class ListDialog(private val list: List<MySpinnerItem>): DialogFragment() {

    interface Listener {
        fun onSelectedItem(dialog: ListDialog, selectedItem: MySpinnerItem)
    }
    private lateinit var listener: Listener

    override fun onAttach(context: Context) {
        super.onAttach(context)
        when {
            parentFragment is Listener -> listener = parentFragment as Listener
            context is Listener -> listener = context
        }
    }

    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        return activity?.let {
            val builder = AlertDialog.Builder(it)
            val items = arrayListOf<String>()
            for (element in list) {
                items.add(element.text)
            }
            val adapter = ArrayAdapter(it, android.R.layout.simple_list_item_1, items)
            builder.setAdapter(adapter) { _, witch ->
                listener.onSelectedItem(this, list[witch])
            }
            builder.create()
        } ?: throw IllegalStateException("Activity cannot be null")
    }
}

package com.example.samplelistdialog

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import com.example.samplelistdialog.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity(), ListDialog.Listener {
    private lateinit var binding: ActivityMainBinding
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        // init fruit dialog
        val listItems = mutableListOf<Fruit>()
        listItems.add(Fruit(100, "apple", "2022-12-31"))
        listItems.add(Fruit(200, "orange", "2023-01-31"))
        listItems.add(Fruit(300, "grape", "2022-12-10"))
        val fruitDialog = ListDialog(listItems)

        // init color dialog
        val colorList = mutableListOf<MyColor>()
        colorList.add(MyColor(10, "white"))
        colorList.add(MyColor(20, "black"))
        colorList.add(MyColor(30, "red"))
        val colorDialog = ListDialog(colorList)

        binding.txvFruit.setOnClickListener {
            fruitDialog.show(supportFragmentManager, "fruit")
        }

        binding.txvColor.setOnClickListener {
            colorDialog.show(supportFragmentManager, "color")
        }
    }

    override fun onSelectedItem(dialog: ListDialog, selectedItem: MySpinnerItem) {
        when(dialog.tag) {
            "fruit" -> {
                val item = selectedItem as Fruit
                val id = item.id
                val name = item.name
                val limit = item.limit
                binding.txvFruit.text = "$id: $name\n$limit"
            }
            "color" -> {
                val item = selectedItem as MyColor
                val id = item.id
                val name = item.name
                binding.txvColor.text = "$id: $name"
            }
        }
    }
}