android kotlin - AlertDialog single choice items example

MainActivity.kt


package com.cfsuman.kotlintutorials

import android.os.Bundle
import android.widget.*
import androidx.appcompat.app.AlertDialog
import androidx.appcompat.app.AppCompatActivity
import com.google.android.material.dialog.MaterialAlertDialogBuilder


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

        val context:MainActivity = this

        // get the widgets reference from XML layout
        val button = findViewById<Button>(R.id.button)
        val textView = findViewById<TextView>(R.id.textView)

        // initial selection (-1 none)
        var selectedIndex:Int = -1


        button.setOnClickListener {
            val builder = MaterialAlertDialogBuilder(context)

            // dialog title
            builder.setTitle("Which is your favorite?")

            val colors = arrayOf(
                "African violet",
                "Alice blue",
                "Alloy orange",
                "Android green",
                "Amaranth pink",
                "Antique bronze"
            )

            // set single choice items
            builder.setSingleChoiceItems(
                colors, // array
                selectedIndex
            ){dialog, i ->}


            // alert dialog positive button
            builder.setPositiveButton("Submit"){dialog,which->
                val position = (dialog as AlertDialog)
                    .listView.checkedItemPosition
                // if selected, then get item text
                if (position !=-1){
                    val selectedItem = colors[position]
                    textView.text = "Favorite color : $selectedItem"
                }
            }

            // alert dialog other buttons
            builder.setNegativeButton("No",null)
            builder.setNeutralButton("Cancel",null)

            // set dialog non cancelable
            builder.setCancelable(false)

            // finally, create the alert dialog and show it
            val dialog = builder.create()
            dialog.show()

            // initially disable the positive button
            dialog.getButton(AlertDialog.BUTTON_POSITIVE)
                .isEnabled = false

            // dialog list item click listener
            dialog.listView.onItemClickListener =
                AdapterView.OnItemClickListener {
                        parent, view, position, id ->
                    // enable positive button when user select an item
                    dialog.getButton(AlertDialog.BUTTON_POSITIVE)
                        .isEnabled = position != -1

                    // set the current selected index
                    selectedIndex = position
                }
        }
    }
}

activity_main.xml


<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#DCDCDC"
    android:padding="24dp">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Show Dialog"
        android:textAllCaps="false"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:fontFamily="sans-serif"
        android:textSize="24sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/button" />

</androidx.constraintlayout.widget.ConstraintLayout>

build.gradle dependencies[add]


// Material components
implementation 'com.google.android.material:material:1.6.1'

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