flex: can i do nice button animation using only flex or do i need adobe flash too?

i would like to add nice animations and other graphics开发者_JAVA技巧 to my application. do i need to use flash to create partial swf files and to load them or is there another way?

Yes, you can do a lot of animations in Flex (although I haven't done anything very complex yet). You should check out Tour de Flex for examples.

Even though Flex offers some TweenEffects (check the list of subclasses), I'd say that animations are better done in Flash CS3/4 as it offers more control on drawing and frames.