What's the “dot” for when registering an Activity

<activityandroid:name=".NewActivity"></activity>

http://developer.android.com/guide/topics/manifest/activity-element.html#nm

android:name
The name of the class that implements the activity, a subclass of Activity. The attribute value should be a fully qualified class name (such as, "com.example.project.ExtracurricularActivity"). However, as a shorthand, if the first character of the name is a period (for example, ".ExtracurricularActivity"), it is appended to the package name specified in the .



As you have noticed the point is not necessary but it basically means: the activity class lives in the same package of the app. So, if your app package is: com.my.package then:

.YourActivity means that your class is inside com.my.package.
YourActivity means that your class is inside com.my.package (same as above).
.activities.YourActivity means that your class is inside com.my.package.activitites.
You can even do something like: com.my.package.activities.YourActivity which is useful when you want to have different versions of your app and use Ant to change the references to the package automatically.