Flutter defining global color resources

Create a file app_colors.dart with the following, add more colors as needed. Color is defined with hex strings. The first FF is the alpha value, the next 2 is for Red, the next 2 is for Green and the last 2 is for Blue

import 'dart:ui';

class AppColors {

  static const primaryColor = Color(0xFFF0E015);
  static const secondaryColor = Color(0xFFAEF015);
  static const accentColor = Color(0xFF15F0BD);

}

Use the color anywhere in the app like this.

import 'package:flutter/material.dart';

import 'app_colors.dart';

class LoadingIndicator extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: CircularProgressIndicator(
          valueColor: new AlwaysStoppedAnimation(AppColors.primaryColor),
        ),
      ),
      backgroundColor: Colors.secondaryColor,
    );
  }
}