Switching application-wide theme programmatically?
Create a base activity for your app and override onCreate to set the theme. Derive all your other activities from this base activity.
Also check this tutorial:
http://www.androidengineer.com/2010/06/using-themes-in-android-applications.html
There may be a good solution to this, but I couldn't find one, so I ended up making a little static helper method in a helper class that takes an Activity and basically performs those two lines you wrote. Sure, it's not perfect, but just adding one short line of code to every onCreate() method in my app was tolerable.