算法把rootview中所有的button改变背景

if (view == null || !(view instanceof ViewGroup))
return; 
Stack m = new Stack<>();
while (view != null) { 
ViewGroup tmpGroup = (ViewGroup) view; 
int count = tmpGroup.getChildCount(); 
for (int i = 0; i < count; i++) {
View child = tmpGroup.getChildAt(i);
if (child instanceof ViewGroup) m.add(child); 
else if (child instanceof Button) { child.setBackgroundColor(color);
} } 
if (m.isEmpty()) break; 
else view = m.pop();
} 
}