MainActivity.kt

class MainActivity : AppCompatActivity() {
  private var toolBar: Toolbar? = null
  private var container: ViewGroup? = null

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    coordinatorLayout {
      fitsSystemWindows = true

      appBarLayout {
        toolBar = toolbar {
          if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) elevation = 4f
        }.lparams(width = matchParent, height = actionBarSize())
      
      }.lparams(width = matchParent)

      container = frameLayout()
        .lparams(width = matchParent, height = matchParent) {
          behavior = AppBarLayout.ScrollingViewBehavior()
        }
    }
  }
}