🎨 Android UIはどのように更新されますか?

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        findViewById<Button>(R.id.button).setOnClickListener {
            Log.d("setOnClickListener", SystemClock.uptimeMillis().toString())
            onClick(findViewById<TextView>(R.id.text_view))
        }
    }

    fun onClick(view: TextView) {
        for (i in 0..4) {
            view.text = i.toString()
            Log.d("for 문 ${i}번째", SystemClock.uptimeMillis().toString())
            SystemClock.sleep(1000)
        }

    }
}