[android] Comments in Android Layout xml

Comments INSIDE tags possible

It's possible to create custom attributes that can be used for commenting/documentation purposes.

In the example below, a documentation:info attribute is defined, with an example comment value:

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:documentation="documentation.mycompany.com"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/relLayoutID"
    documentation:info="This is an example comment" >

    <TextView
        documentation:purpose="Instructions label"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Click here to begin."
        android:id="@+id/tvMyLabel"
        android:layout_alignParentTop="true"
        android:layout_alignParentStart="true"
        documentation:info="Another example comment"
        documentation:translation_notes="This control should use the fewest characters possible, as space is limited"
        />

</RelativeLayout>

Note that in this case, documentation.mycompany.com is just a definition for the new custom XML namespace (of documentation), and is thus just a unique URI string - it can be anything as long as it's unique. The documentation to the right of the xmlns: can also be anything - this works the same way that the android: XML namespace is defined and used.

Using this format, any number of attributes can be created, such as documentation:info, documentation:translation_notes etc., along with a description value, the format being the same as any XML attribute.

In summary:

• Add a xmls:my_new_namespace attribute to the root (top-level) XML element in the XML layout file. Set its value to a unique string
• Under any child XML element within the file, use the new namespace, and any word following to define comment tags that are ignored when compiled, e.g. <TextView my_new_namespace:my_new_doc_property="description" />