Border around controls

For example we have view:

<TextView
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:text="Hello World!"
	android:background="@drawable/black"/>

Notice line:

android:background="@drawable/black"

This means that I've created new file in drawable folder /app/src/main/res/drawable/black.xml which looks like:

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
    <solid android:color="#ffffff" />
    <stroke android:width="1dip" android:color="#000000"/>
</shape>