Changes icon color by using Floating Action Button

I want to change the Icon color by using a Floating Action Button. If I press red button, the icon changes into red color.

Code :

floatingActionButton: Row(
      mainAxisAlignment: MainAxisAlignment.end,
      children: <Widget>[
        FloatingActionButton.extended(
          icon: Icon(Icons.colorize),
          label: Text('Red'),
          backgroundColor: Colors.red,
        ),

You can do like this (use StatefulWidget widget and setState):

class ChangeIconColor extends StatefulWidget {
  @override
  ChangeIconColorState createState() => ChangeIconColorState();
}

class ChangeIconColorState extends State<ChangeIconColor> {
  
  Color selectedColor = Colors.blue;
  
  changeColor(Color color){
    setState(() {
      selectedColor = color;
    });
  }
  
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: Row(mainAxisAlignment: MainAxisAlignment.end, children: <Widget>[
        FloatingActionButton.extended(
          onPressed: () {
            changeColor(Colors.red);
          },
          icon: Icon(Icons.colorize),
          label: Text('Red'),
          backgroundColor: Colors.red,
        ),
      ]),
      body: Container(
          child: Icon(
        Icons.lock_clock,
        color: selectedColor,
      )),
    );
  }
}

if you want to use StatelessWidget you can use ValueNotifier like this:

class ChangeIconColorState extends StatelessWidget {
  final ValueNotifier<Color> selectedColorNotifier = ValueNotifier(Colors.blue);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      floatingActionButton: Row(mainAxisAlignment: MainAxisAlignment.end, children: <Widget>[
        FloatingActionButton.extended(
          onPressed: () {
            selectedColorNotifier.value = Colors.red;
          },
          icon: Icon(Icons.colorize),
          label: Text('Red'),
          backgroundColor: Colors.red,
        ),
      ]),
      body: Container(
          child: ValueListenableBuilder(
        builder: (context, Color color, child) {
          return Icon(
            Icons.lock_clock,
            color: color,
          );
        },
        valueListenable: selectedColorNotifier,
      )),
    );
  }
}