android kotlin - ChipGroup get selected chips

MainActivity.kt


package com.cfsuman.kotlintutorials

import android.app.Activity
import android.content.res.ColorStateList
import android.graphics.Color
import android.os.Bundle
import android.widget.TextView
import androidx.core.view.children
import com.google.android.material.chip.Chip
import com.google.android.material.chip.ChipGroup


class MainActivity : Activity() {
    private lateinit var chipGroup:ChipGroup
    private lateinit var textView:TextView

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

        // get the widgets reference from XML layout
        chipGroup = findViewById(R.id.chipGroup)
        textView = findViewById(R.id.textView)

        // get chip group initially checked chips
        handleSelection()

        // set checked change listener for each chip on chip group
        chipGroup.children.forEach {
            (it as Chip).setOnCheckedChangeListener { 
                    buttonView, isChecked ->
                handleSelection()
            }
        }
    }


    // function to get chip group checked chips
    private fun handleSelection(){
        textView.text = "Checked Chips : "
        chipGroup.checkedChipIds.forEach{
            val chip = findViewById<Chip>(it)
            textView.append("\n${chip.text}")
        }
    }
}

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="32dp">

    <com.google.android.material.chip.ChipGroup
        android:id="@+id/chipGroup"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        app:singleSelection="false"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent">

        <com.google.android.material.chip.Chip
            android:id="@+id/chipRed"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@style/Widget.MaterialComponents.Chip.Filter"
            android:text="Red" />

        <com.google.android.material.chip.Chip
            android:id="@+id/chipGreen"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@style/Widget.MaterialComponents.Chip.Filter"
            android:checked="true"
            android:text="Green" />

        <com.google.android.material.chip.Chip
            android:id="@+id/chipYellow"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@style/Widget.MaterialComponents.Chip.Filter"
            android:text="Yellow" />

        <com.google.android.material.chip.Chip
            android:id="@+id/chipBlue"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@style/Widget.MaterialComponents.Chip.Filter"
            android:checked="true"
            android:text="Blue" />

        <com.google.android.material.chip.Chip
            android:id="@+id/chipBlack"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            style="@style/Widget.MaterialComponents.Chip.Filter"
            android:text="Black" />

    </com.google.android.material.chip.ChipGroup>

    <TextView
        android:id="@+id/textView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:fontFamily="sans-serif-condensed-medium"
        android:gravity="center"
        android:padding="8dp"
        android:textColor="#4F42B5"
        android:textSize="22sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/chipGroup"
        tools:text="TextView" />

</androidx.constraintlayout.widget.ConstraintLayout>