DHosseiny

class Optional<T> {

    private var value: T? = null

    private constructor() {
        this.value = null
    }

    private constructor(value: T) {
        this.value = value

DHosseiny

class MainActivity : AppCompatActivity() {
    private val messageView : TextView by lazy {
        // runs on first access of messageView
        findViewById(R.id.message_view) as TextView
    }
  
   override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        setContentView(R.layout.activity_main)

DHosseiny

import android.databinding.DataBindingUtil;
import android.databinding.ViewDataBinding;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

/**
 * Created by Davud. MyApplication project.
 */