how to setItem of an image adapter (extending BaseAdapter) attached to a GridView

[antvalencia]

i see an implemented abstract getItem method in various example code posts for an ImageAdapter (including the android dev site), but would like to implement a setItem method. or, at least a setItem method is what i think i'm after, but the one i've implemented is not changing the image. how would one update an image, where the int position is provided, and the image in the example from the aforementioned link would get updated to say, R.drawable.sample_2? thanks in advance for your help!