Apply a theme to an Activity or application

Apply a theme to an Activity or application

To set a theme for all the activities of your application, open the

AndroidManifest.xml

file andedit the

<application>

tag to include the

android:theme

attribute with the style name. For example:

<application android:theme="@style/CustomTheme">

If you want a theme applied to just one Activity in your application, then add the

android:theme

attribute to the

<activity>

tag instead.
http://developer.android.com/guide/topics/ui/themes.html#ApplyATheme