RecyclerViewExtensions.kt

import android.support.v7.widget.RecyclerView
import android.view.View
import android.view.View.GONE
import android.view.View.VISIBLE

fun RecyclerView.setEmptyView(view: View) {
  adapter?.apply {
    val observer = object: RecyclerView.AdapterDataObserver() {
      override fun onChanged() {
        view.visibility = if (adapter.isEmpty()) VISIBLE else GONE
        this@setEmptyView.visibility = if (adapter.isEmpty()) GONE else VISIBLE
      }
    }
    registerAdapterDataObserver(observer)
    observer.onChanged()
  }
}

fun <A: RecyclerView.ViewHolder> RecyclerView.Adapter<A>.isEmpty() = itemCount == 0