That's enough theory, especially with something that should be so visible. Let's build an animation demo app that explores everything we have just discussed, and a bit more.
This app involves little amounts of code in lots of different files. Therefore, I have tried to make it plain what code is in which file so you can keep track of what is going on. This will make the Java we write for this app more understandable as well.
The app will demonstrate rotations, fades, translations, animation events, interpolations, and controlling duration with SeekBar. The best way to explain what SeekBar does is to build it and then watch it in action.