Android - Swipe to Delete and Undo in RecyclerView with Kotlin

package com.gtappdevelopers.kotlingfgproject

data class CourseRVModal(
    // on below line we are creating a 
    // two variable one for course 
    // name and other for course image
    var courseName: String,
    var courseImg: Int
)

package com.gtappdevelopers.kotlingfgproject

import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView

// on below line we are creating 
// a course rv adapter class.
class CourseRVAdapter(
    // on below line we are passing variables
    // as course list and context
    private val courseList: ArrayList<CourseRVModal>,
    private val context: Context
) : RecyclerView.Adapter<CourseRVAdapter.CourseViewHolder>() {
    override fun onCreateViewHolder(
        parent: ViewGroup,
        viewType: Int
    ): CourseRVAdapter.CourseViewHolder {
        // this method is use to inflate the layout file 
        // which we have created for our recycler view.
        // on below line we are inflating our layout file.
        val itemView = LayoutInflater.from(parent.context).inflate(
            R.layout.course_rv_item,
            parent, false
        )
        // at last we are returning our view holder 
        // class with our item View File.
        return CourseViewHolder(itemView)
    }

    override fun onBindViewHolder(holder: CourseRVAdapter.CourseViewHolder, position: Int) {
        // on below line we are setting data to our text view and our image view.
        holder.courseNameTV.text = courseList.get(position).courseName
        holder.courseIV.setImageResource(courseList.get(position).courseImg)
    }

    override fun getItemCount(): Int {
        // on below line we are returning 
        // our size of our list
        return courseList.size
    }

    class CourseViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
        // on below line we are initializing our course name
        // text view and our image view.
        val courseNameTV: TextView = itemView.findViewById(R.id.idTVCourse)
        val courseIV: ImageView = itemView.findViewById(R.id.idIVCourse)
    }
}

package com.gtappdevelopers.kotlingfgproject

import android.os.Bundle
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.ItemTouchHelper
import androidx.recyclerview.widget.RecyclerView
import com.google.android.material.snackbar.Snackbar

class MainActivity : AppCompatActivity() {

    // on below line we are creating variables for
    // our swipe to refresh layout, recycler view, adapter and list.
    lateinit var courseRV: RecyclerView
    lateinit var courseRVAdapter: CourseRVAdapter
    lateinit var courseList: ArrayList<CourseRVModal>

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        
        // on below line we are initializing
        // our views with their ids.
        courseRV = findViewById(R.id.idRVCourses)

        // on below line we are initializing our list
        courseList = ArrayList()

        // on below line we are initializing our adapter
        courseRVAdapter = CourseRVAdapter(courseList, this)

        // on below line we are setting adapter
        // to our recycler view.
        courseRV.adapter = courseRVAdapter

        // on below line we are adding data to our list
        courseList.add(CourseRVModal("Android Development", R.drawable.android))
        courseList.add(CourseRVModal("C++ Development", R.drawable.c))
        courseList.add(CourseRVModal("Java Development", R.drawable.java))
        courseList.add(CourseRVModal("Python Development", R.drawable.python))
        courseList.add(CourseRVModal("JavaScript Development", R.drawable.js))

        // on below line we are notifying adapter
        // that data has been updated.
        courseRVAdapter.notifyDataSetChanged()

        // on below line we are creating a method to create item touch helper
        // method for adding swipe to delete functionality.
        // in this we are specifying drag direction and position to right
        // on below line we are creating a method to create item touch helper
        // method for adding swipe to delete functionality.
        // in this we are specifying drag direction and position to right
        ItemTouchHelper(object : ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.RIGHT) {
            override fun onMove(
                recyclerView: RecyclerView,
                viewHolder: RecyclerView.ViewHolder,
                target: RecyclerView.ViewHolder
            ): Boolean {
                // this method is called
                // when the item is moved.
                return false
            }

            override fun onSwiped(viewHolder: RecyclerView.ViewHolder, direction: Int) {
                // this method is called when we swipe our item to right direction.
                // on below line we are getting the item at a particular position.
                val deletedCourse: CourseRVModal =
                    courseList.get(viewHolder.adapterPosition)

                // below line is to get the position
                // of the item at that position.
                val position = viewHolder.adapterPosition

                // this method is called when item is swiped.
                // below line is to remove item from our array list.
                courseList.removeAt(viewHolder.adapterPosition)

                // below line is to notify our item is removed from adapter.
                courseRVAdapter.notifyItemRemoved(viewHolder.adapterPosition)

                // below line is to display our snackbar with action.
                // below line is to display our snackbar with action.
                // below line is to display our snackbar with action.
                Snackbar.make(courseRV, "Deleted " + deletedCourse.courseName, Snackbar.LENGTH_LONG)
                    .setAction(
                        "Undo",
                        View.OnClickListener { 
                            // adding on click listener to our action of snack bar.
                            // below line is to add our item to array list with a position.
                            courseList.add(position, deletedCourse)

                            // below line is to notify item is
                            // added to our adapter class.
                            courseRVAdapter.notifyItemInserted(position)
                        }).show()
            } 
            // at last we are adding this
            // to our recycler view.
        }).attachToRecyclerView(courseRV)

    }
}