state_loading.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:gravity="center">
        <ProgressBar
            style="@style/Widget.AppCompat.ProgressBar.Horizontal"
            android:layout_width="120dp"
            android:layout_height="wrap_content"
            android:indeterminate="true" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal"
            android:layout_marginBottom="8dp"
            android:text="@string/loading_data"
            android:textSize="18sp"
            android:textColor="?android:attr/textColorPrimary"/>
    </LinearLayout>
</layout>