Challenge 1: Logging Every Lifecycle Callback — Solution

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        Log.d("MainActivity", "onCreate called")
    }

    override fun onStart() {
        super.onStart()
        Log.d("MainActivity", "onStart called")
    }

    override fun onResume() {
        super.onResume()
        Log.d("MainActivity", "onResume called")
    }

    override fun onPause() {
        super.onPause()
        Log.d("MainActivity", "onPause called")
    }

    override fun onStop() {
        super.onStop()
        Log.d("MainActivity", "onStop called")
    }

    override fun onDestroy() {
        super.onDestroy()
        Log.d("MainActivity", "onDestroy called")
    }
}

Walkthrough:
1. Add all six overrides above to MainActivity.kt, run the app.
2. On first launch, Logcat shows: onCreate, onStart, onResume — in that
   order.
3. Rotate the emulator (Ctrl+F11 on Windows/Linux, or the rotate icon in
   the emulator's side toolbar).
4. Logcat then shows: onPause, onStop, onDestroy, onCreate, onStart,
   onResume — the entire Activity was destroyed and recreated from
   scratch by the rotation.

Notes:
- The rotation behavior (full destroy + recreate) is the default and is
  exactly why savedInstanceState (Challenge 2) matters — without it, any
  var holding UI state (a counter, typed text, a scroll position) resets
  to its initial value after every rotation.
- Pressing Home (not rotating) instead produces onPause, onStop only —
  the Activity is stopped but NOT destroyed, since it might be resumed
  later without needing to be recreated.