MainActivity.kt

package com.example.myapplication

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.view.View
import androidx.databinding.DataBindingUtil
import com.example.myapplication.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

    private lateinit var binding: ActivityMainBinding

    private val myName: MyName = MyName("Aleks Haecky")

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        binding = DataBindingUtil.setContentView<ActivityMainBinding>(this, R.layout.activity_main)

        binding.doneButton.setOnClickListener { onButtonClicked() }
        binding.userName = myName
    }

    private fun onButtonClicked() {
        binding.apply{
            nicknameText.visibility = View.VISIBLE
            nicknameEdit.visibility = View.GONE
            doneButton.visibility = View.GONE
        }

        myName.nickname = binding.nicknameEdit.text.toString()
        binding.invalidateAll()
    }
}