android kotlin - ChipGroup add chip programmatically

MainActivity.kt


package com.example.jetpack

import android.content.Context
import android.os.Bundle
import android.view.View
import android.widget.Button
import androidx.appcompat.app.AppCompatActivity
import com.google.android.material.chip.Chip
import com.google.android.material.chip.ChipGroup
import kotlinx.android.synthetic.main.activity_main.*


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

        val context = this

        // 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}"
            }
        }


        // add chip to chip group programmatically
        button.setOnClickListener {
            (it as Button).isEnabled = false
            chipGroup.addChip(context,"Magenta")
            chipGroup.addChip(context,"Pink")
            chipGroup.addChip(context,"Black")
        }
    }
}


// create chip programmatically and add it to chip group
fun ChipGroup.addChip(context: Context, label: String){
    Chip(context).apply {
        id = View.generateViewId()
        text = label
        isClickable = true
        isCheckable = true
        isCheckedIconVisible = false
        isFocusable = true
        addView(this)
    }
}

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">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:text="add Chips"
        android:backgroundTint="#E97451"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.chip.ChipGroup
        android:id="@+id/chipGroup"
        style="@style/Widget.MaterialComponents.ChipGroup"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:layout_marginTop="24dp"
        android:layout_marginEnd="8dp"
        app:checkedChip="@id/chipGreen"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button"
        app:selectionRequired="true"
        app:singleSelection="true">

        <com.google.android.material.chip.Chip
            android:id="@+id/chipRed"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:checkable="true"
            android:text="Red"
            app:checkedIconVisible="false" />

        <com.google.android.material.chip.Chip
            android:id="@+id/chipGreen"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:checkable="true"
            android:text="Green"
            app:checkedIconVisible="false" />

        <com.google.android.material.chip.Chip
            android:id="@+id/chipYellow"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:checkable="true"
            android:text="Yellow"
            app:checkedIconVisible="false" />

    </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>