Why all attributes are prefixed?

Question

What is the design advantage to do this

<TextView
    android:layout_width="105px"
    android:layout_height="wrap_content"
    android:text="@string/hello"
    />

and not this

<android:TextView
    layout_width="105px"
    layout_height="wrap_content"
    text="@string/hello"
    />

Is that android: prefix everywhere not a little bit to chatty?

Answer 1

android is a namespace prefix and it is used to tell that those attributes are in the XML namespace bound to that prefix. You should have a namespace declaration somewhere in your XML document which looks like xmlns:android = "the namespace URI here". It is quite unusual to prefix attributes but it is necessary when attributes of a given XML vocabulary are found in XML elements not belonging to that vocabulary because it avoids collisions.

Answer 2

In XML, attributes have to be prefixed in order to be in a namespace; they don't automatically pick up the namespace of the element.