GoodClick.kt

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val model: MainViewModel by viewModels()

        button.setOnClickListener {
            model.onButtonClick()
        }

        model.displayText.observe(this, Observer { text ->
            text_view.text = text
        })
    }
}

class MainViewModel : ViewModel() {

    private val _displayText = MutableLiveData<String>()
    val displayText: LiveData<String>
        get() = _displayText

    fun onButtonClick() {
        _displayText.postValue("I would really use a string resource!")
    }
}