When developing for the android platform we can separate the resources we use from the code. Doing so, we can handle the resources without having the need to update the code. In terms of maintainability it is highly recommended to keep that separation.
Some of the resources cannot be handheld otherwise. So is the case when dealing with images. Other resources can be handheld without treating them as resources. So is the case (for instance) with colors, arrays, xml and the user interface.
I have just completed to update the slides about using resources in the Android Fundamentals course at www.abelski.com and added these video clips (links to these clips are available within the slides themselves).