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2022.10.1

kotlin リスト選択ダイアログを使う

DialogFragmentを継承したリスト選択ダイアログを作成し、
選択されたアイテムを任意のデータ型で取得する内容です。
IdとName属性を持つData Classで取得しています。

MySpinnerItem.kt

package com.example.samplelistdialog

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

ListDialog.kt

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: MutableList<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.name)
            }
            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")
    }
}

MainActivity.kt

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
        val listItems = mutableListOf<MySpinnerItem>()
        listItems.add(MySpinnerItem(100, "apple"))
        listItems.add(MySpinnerItem(200, "orange"))
        listItems.add(MySpinnerItem(300, "grape"))

        val fruitDialog = ListDialog(listItems)

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

    override fun onSelectedItem(dialog: ListDialog, selectedItem: MySpinnerItem) {
        when(dialog.tag) {
            "fruit" -> {
                val id = selectedItem.id
                val name = selectedItem.name
                val str = "$id: $name"
                binding.txvSample.text = str
            }
        }
    }
}
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