add/delete student

import java.util.Scanner
import kotlin.system.exitProcess

val scanner = Scanner(System.`in`)

class Program1{
    var studentName: MutableList<String> = ArrayList()  //don't make it private so we can access it in main function
    fun addStudent(){
        print("\nEnter student name: ")
        val name = readLine()!!
        studentName.add(name)
    }
    fun deleteStudent(){
        val result = studentName.toMutableList()
         /*if student in list is 1 and
          *when delete function is called it automatically removes the only student in list
          *without giving the specific index
          */
        studentName = if(studentName.size == 1) {
            result.removeAt(0)
            result
        } else {
            print("Enter index to delete: ")
            val index = scanner.nextInt()
            result.removeAt(index)
            result
        }
    }
    fun displayStudent(){
            println("List of students: ")
            var index = 0
            for (name in studentName) {
                println("[$index]$name")
                index += 1
            }
    }
}
fun main(){
    val call = Program1()
    while(true){
    println("\n[1]Add Student [2]Delete Student [3] Display All Student [Other Key]Exit ")
    print("Answer: ")

        when (scanner.next().single()) {
            '1' -> call.addStudent()
            '2' -> if(call.studentName.isNotEmpty()){call.deleteStudent()} else println("No student in list")
            '3' -> if(call.studentName.isNotEmpty()){call.displayStudent()} else println("No student in list")
            else -> exitProcess(0) //break the infinite loop (exit app)
        }
    }
}