Hello Android Example

activity_main.xml xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/root_layout" android:layout_width="match_parent" android:layout_height="match_parent" android:padding="16dp"

activity_main.xml xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/root_layout" android:layout_width="match_parent" android:layout_height="match_parent" android:padding="16dp"

activity_main.xml xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/coordinator_layout" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#84967c" > android:id="@+id/btn_play"