Wednesday, March 4, 2020

android kotlin - AlertDialog multiple choice example

MainActivity.kt 

package com.example.jetpack

import android.os.Bundle
import android.widget.AdapterView
import androidx.appcompat.app.AlertDialog
import androidx.appcompat.app.AppCompatActivity
import com.google.android.material.dialog.MaterialAlertDialogBuilder
import kotlinx.android.synthetic.main.activity_main.*


class MainActivity : AppCompatActivity() {

    private var initialCheckedItems =  mutableListOf<Boolean>()

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

        val context = this

        button.setOnClickListener {
            val builder = MaterialAlertDialogBuilder(context)

            // dialog title
            builder.setTitle("Select favorite colors (min 2)")

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

            if (initialCheckedItems.isEmpty()){
                repeat(colors.count()) {initialCheckedItems.add(false)}
            }

            builder.setMultiChoiceItems(
                colors,
                initialCheckedItems.toBooleanArray()
            ) { dialog, which, isChecked ->}


            // alert dialog positive button
            builder.setPositiveButton("Submit"){dialog,which->
                val alertDialog = dialog as AlertDialog
                val sparseBooleanArray = alertDialog.listView.checkedItemPositions
                var counter = 0

                textView.text = ""
                colors.forEachIndexed { index, s ->
                    if (sparseBooleanArray.get(index, false)) {
                        textView.append("\n$s")
                        counter += 1
                    }
                }

                if (counter > 0) {
                    textView.text = "Selected colors: " + textView.text
                }
            }


            // alert dialog neutral button
            builder.setNeutralButton("Cancel"){dialog,which->
                textView.text = ""
            }

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

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

            // initially enable disable the positive button
            if((initialCheckedItems.filter { it }).size < 2){
                dialog.getButton(AlertDialog.BUTTON_POSITIVE).isEnabled = false
            }


            // dialog list item click listener
            dialog.listView.onItemClickListener =
                AdapterView.OnItemClickListener { parent, view, position, id ->
                    val sparseBooleanArray = dialog.listView.checkedItemPositions
                    var checkedItems = 0
                    colors.forEachIndexed { index, s ->
                        if (sparseBooleanArray.get(index,false)){
                            checkedItems +=1
                            initialCheckedItems[index] = true
                        }else{
                            initialCheckedItems[index] = false
                        }
                    }

                    dialog.getButton(AlertDialog.BUTTON_POSITIVE)
                        .isEnabled = checkedItems >=2
                }
        }
    }
}
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:id="@+id/constraintLayout"
    tools:context=".MainActivity">

    <com.google.android.material.button.MaterialButton
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="Show Dialog"
        android:backgroundTint="#E30022"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        tools:text="TextView"
        android:textAppearance="@style/TextAppearance.AppCompat.Large"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button" />

</androidx.constraintlayout.widget.ConstraintLayout>
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