android-tools-namespace

Starting with a recent new version of ADT, I've noticed this new attribute on the layout XML files, for example: <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" tools:context=".MainActivity" /> What is "tools:context" used for? How does it even know the exact path to the activity that is written there? Does it look at the package of the app, inside the manifest? Is it limited to classes that extend Context or only

Here is an example of the app namespace that I've seen from a res/menu/main.xml file <menu 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" tools:context=".MainActivity" > <item android:id="@+id/action_settings" android:title="@string/action_settings" android:orderInCategory="100" app:showAsAction="never" /> </menu> What purpose does the app namespace serve? Is it a "standard" Android XML namespace? Are the same value options available for the same attribute placed in two different