title: Android: Fade view in and out
body: <p>I need to display an image button that fades in and out (and in and out and so on...)
  The transparency can be set with setAlpha but how can I fade in and out? I mean I cannot do it on another thread because you need to do such things on the UI thread, right?</p>
  
  <p>I guess it can be done with animations but I haven't found anything, because I don't have any experience with animations and don't really know what to search for...</p>
  
  <p>Actually what I really want is to fade one image in and another one out but I guess the easiest way is to place the first image button below the second and just fade the second one. Or is there an easier way to do it?</p>