Initializing Properties in Kotlin: by lazy or lateinit — Which to Choose?

Hello everyone! I just started learning Kotlin and ran into a problem. I'm writing a small application, and I need to initialize some class properties, but their values become known only later — for example, after loading data or in `onCreate` for Android. I know two approaches: `lateinit` and `by lazy`. But I can't figure out when to use which. Here's an example of my code: ```kotlin class MyActivity : AppCompatActivity() { private lateinit var userName: String private val userAge: Int by lazy { fetchUserAge() // this method may be called later } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) userName = "John" // lateinit initialization } private fun fetchUserAge(): Int { return 25 } } ``` The problem is that if I use `lateinit` for `userName`, the IDE complains if I try to make it `val`. And `by lazy` only works with `val`. Also, I heard that `latei