activity_cryptocurrencies.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="8dp"
    tools:context="co.cdmunoz.cryptocurrencyapp.ui.list.CryptocurrenciesActivity"
    >

  <android.support.v7.widget.RecyclerView
      android:id="@+id/recycler"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      />
  <ProgressBar
      android:id="@+id/progressBar"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_centerVertical="true"
      style="?android:attr/progressBarStyle"
      android:visibility="gone"
      />

</RelativeLayout>