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

Question

I\'m kind of a noob at programming for the Android OS. I noticed in the books I have been reading that the authors have placed a \"dot\" in front of the activity name when

Answer 1

That dot will append your package in your application manifest.

If your package name is com.app.demo.

<activity android:name=".HelloWorldActivity">

It means that Activity is lying inside demo package.

You can replace this with

<activity android:name="com.app.demo.HelloWorldActivity">

Answer 2

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 <manifest>.

So given ApplicationManifest.xml:

<manifest 
    ...
    package="com.stackoverflow.android.geotask"
    ...>
    <application ...>
        <activity android:name=".view.TaskListListView" ...>
        ...
    </application>
</manifest> 

then since android:name=".view.TaskListListView" has a leading period, so it is interpreted as android:name="com.stackoverflow.android.geotask.view.TaskListListView".

Answer 3

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.