Android button setColorFilter behaviour

Question

(I changed the question a bit, because the problem is a bit clearer now)

I have 4 buttons on my application, and when a user clickes certain button I change that but

Answer 1

The Drawable documentation regarding setColorFilter(ColorFilter cf) states that 'null' may be passed to remove any existing filters. So, perhaps it could be that once the TRANSPARENT filter has been applied, then your subsequent GREEN filter can't be seen? I don't know enough about .setColorFilter and PorterDuff to know for sure, but it's worth a shot. Perhaps try:

d.setColorFilter(null); 
d.setColorFilter(filter); 

Also you could instead use this method:

setColorFilter(int color, PorterDuff.Mode mode)