How to Create Expandable RecyclerView items in Android using Kotlin?

// this is the Language model class
class Language(
    val name : String ="",
    val description : String= "",
    var expand : Boolean = false
)

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import com.geeksforgeeks.rvadapterviewbinding.databinding.SingleItemBinding

class RvAdapter(
    private var languageList: List<Language>
) : RecyclerView.Adapter<RvAdapter.ViewHolder>() {

    // create an inner class with name ViewHolder
    // It takes a view argument, in which pass the generated class of single_item.xml
    // ie SingleItemBinding and in the RecyclerView.ViewHolder(binding.root) pass it like this
    inner class ViewHolder(val binding: SingleItemBinding) : RecyclerView.ViewHolder(binding.root)

    // inside the onCreateViewHolder inflate the view of SingleItemBinding
    // and return new ViewHolder object containing this layout
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val binding = SingleItemBinding.inflate(LayoutInflater.from(parent.context), parent, false)
        return ViewHolder(binding)
    }

    // bind the items with each item of the list languageList which than will be
    // shown in recycler view
    // to keep it simple we are not setting any image data to view
    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        with(holder){
            with(languageList[position]){
                // set name of the language from the list
                binding.tvLangName.text = this.name
                // set description to the text
                // since this is inside "expandedView" its visibility will be gone initially
                // after click on the item we will make the visibility of the "expandedView" visible
                // which will also make the visibility of desc also visible
                binding.tvDescription.text = this.description
                // check if boolean property "extend" is true or false
                // if it is true make the "extendedView" Visible
                binding.expandedView.visibility = if (this.expand) View.VISIBLE else View.GONE
                // on Click of the item take parent card view in our case
                // revert the boolean "expand"
                binding.cardLayout.setOnClickListener {
                    this.expand = !this.expand
                    notifyDataSetChanged()
                }
            }
        }
    }
    // return the size of languageList
    override fun getItemCount(): Int {
        return languageList.size
    }
}

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.recyclerview.widget.LinearLayoutManager
import com.geeksforgeeks.rvadapterviewbinding.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

    // view binding for the activity
    private var _binding: ActivityMainBinding? = null
    private val binding get() = _binding!!

    // get reference to the adapter class
    private var languageList = ArrayList<Language>()
    private lateinit var rvAdapter: RvAdapter

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        _binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        // define layout manager for the Recycler view
        binding.rvList.layoutManager = LinearLayoutManager(this)
        
        // attach adapter to the recycler view
        rvAdapter = RvAdapter(languageList)
        binding.rvList.adapter = rvAdapter

        // create new objects
        // add some row data
        val language1 = Language(
            "Java",
            "Java is an Object Oriented Programming language." +
                    " Java is used in all kind of applications like Mobile Applications (Android is Java based), " +
                    "desktop applications, web applications, client server applications, enterprise applications and many more. ",
            false
        )
        val language2 = Language(
            "Kotlin",
            "Kotlin is a statically typed, general-purpose programming language" +
                    " developed by JetBrains, that has built world-class IDEs like IntelliJ IDEA, PhpStorm, Appcode, etc.",
            false
        )
        val language3 = Language(
            "Python",
            "Python is a high-level, general-purpose and a very popular programming language." +
                    " Python programming language (latest Python 3) is being used in web development, Machine Learning applications, " +
                    "along with all cutting edge technology in Software Industry.",
            false
        )
        val language4 = Language(
            "CPP",
            "C++ is a general purpose programming language and widely used now a days for " +
                    "competitive programming. It has imperative, object-oriented and generic programming features. ",
            false
        )

        // add items to list
        languageList.add(language1)
        languageList.add(language2)
        languageList.add(language3)
        languageList.add(language4)

        rvAdapter.notifyDataSetChanged()

    }

    // on destroy of view make the binding reference to null
    override fun onDestroy() {
        super.onDestroy()
        _binding = null
    }
}