hluhovskyi

private val errorMessage: TextView by ViewFinderDelegate(R.id.error_message)

hluhovskyi

class ViewFinderDelegate<T : View> : ReadOnlyProperty<Activity, T> {
  
    private object EMPTY 
    private val id: Int
    private var view: Any? = Empty
  
    constructor(@IdRes id: Int) {
        this.id = id
    }
  

hluhovskyi

private val errorMessage: TextView by lazy { getViewById(R.id.error_message) }

hluhovskyi

private lateinit var errorMessage: TextView
…
override fun onCreate(savedInstanceState: Bundle?) {
    …
    errorMessage = getViewById(R.id.error_message)
}

hluhovskyi

fun <T : View> Activity.getViewById(@IdRes id: Int): T {
    return findViewById(id) as T
}

hluhovskyi

private TextView errorMessage;
…
@Override
protected void onCreate(Bundle savedInstanceState) {
    errorMessage = (TextView) findViewById(R.id.error_message);
}

hluhovskyi

private lateinit var errorMessage: TextView
…
override fun onCreate(savedInstanceState: Bundle?) {
    …
    errorMessage = findViewById(R.id.error_message) as TextView
}