android kotlin - ChipGroup single selection

MainActivity.kt


package com.example.jetpack

import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import com.google.android.material.chip.Chip
import kotlinx.android.synthetic.main.activity_main.*


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

        // get chip group initial checked chip text
        val chip: Chip? = findViewById(chipGroup.checkedChipId)
        textView.text = "Checked Chip : ${chip?.text}"


        // set chip group checked change listener
        chipGroup.setOnCheckedChangeListener { group, checkedId ->
            // get the checked chip instance from chip group
            (findViewById<Chip>(checkedId))?.let {
                // Show the checked chip text on text view
                textView.text = "Checked Chip : ${it.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:id="@+id/constraintLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FEFEFA"
    tools:context=".MainActivity">

    <com.google.android.material.chip.ChipGroup
        android:id="@+id/chipGroup"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="32dp"
        android:layout_marginEnd="8dp"
        app:singleSelection="true"
        app:selectionRequired="true"
        app:checkedChip="@id/chipGreen"
        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.Choice"
            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.Choice"
            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.Choice"
            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.Choice"
            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.Choice"
            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>