Flutter: random color

import 'dart:math' as math;
import 'package:flutter/material.dart';

void main() => runApp(App());

class App extends StatefulWidget {
  @override
  _AppState createState() => _AppState();
}

class _AppState extends State<App> {
  Color color = Colors.red;
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Container(
                width: 200,
                height: 200,
                color: color,
              ),
              RaisedButton(
                onPressed: () {
                  setState(() {
                    color = randomColor();
                  });
                },
                child: Text('Random color'),
              ),
            ],
          ),
        ),
      ),
    );
  }

  int random(int min, int max) {
    final _random = math.Random();
    return min + _random.nextInt(max - min + 1);
  }

  Color randomColor() {
    return Color.fromARGB(
        random(150, 255), random(0, 255), random(0, 255), random(0, 255));
  }
}