A bug was filed on android.com recently that had me poring through the code and docs to understand three boolean flags in the old Animation class: fillBefore , fillAfter , and fillEnabled . On the surface, these properties don't seem that difficult to understand; they control how animations behave before and after they run. But between some complicated interactions of the properties and some, er, inaccuracies in the reference docs, it turned out to be somewhat tricky to understand how they work and how they're supposed to work. Once I got through that exercise (including fixing the docs - look for those fixes in a future release), I thought it might be helpful to explain how these flags really work. First, let's cover the behavior of fillBefore and fillAfter . We'll get to fillEnabled and it's, um, special behavior after that. Before and After fillBefore and fillAfter are pretty simple, conceptually; they define how an animation behaves before and after it runs...