Думаю, это должно сработать.
class HomeBottomNavigationBar extends StatefulWidget {
@override
_HomeBottomNavigationBarState createState() =>_HomeBottomNavigationBarState();
}
class _HomeBottomNavigationBarState extends State<HomeBottomNavigationBar>
{
int pressedButtonNo = 0;
@override
Widget build(BuildContext context) {
return CurvedNavigationBar(
items: <Widget>[
Icon(Icons.add, size: 30, color: (pressedButtonNo = 0)? Colors.Green : Colors.Black,),
Icon(Icons.list, size: 30, color: (pressedButtonNo = 1)? Colors.Green : Colors.Black,),
Icon(Icons.compare_arrows, size: 30, color: (pressedButtonNo = 2)? Colors.Green : Colors.Black,),
],
onTap: (index) {
setState () {
pressedButtonNo = index;
}
},
);
}}
Я не тестировал. Надеюсь, что это работает! Удачного кодирования :)