Flutter 中Color 使用

      bottomNavigationBar: BottomNavigationBar(
        items: const<BottomNavigationBarItem>[
          BottomNavigationBarItem(
              icon: Icon(Icons.home), title: Text("Home")),
          BottomNavigationBarItem(
              icon: Icon(Icons.cake), title: Text("Center")),
          BottomNavigationBarItem(
              icon: Icon(Icons.edit), title: Text("End")),

        ],
        currentIndex: _selectIndex,
        unselectedItemColor: Colors.blue,
        backgroundColor: Color(0xFFff5656),
        selectedFontSize: 22,
        selectedItemColor: Colors.amber[900],
        onTap: _onItemTapped,
      ),

backgroundColor: Color(0xFFff5656),  //红色  严格按照 0x +透明度+red+green+blue
selectedItemColor: Colors.amber[900],  //琥珀色 

import 'package:flutter/material.dart';

class CostomColors {
  static const Color colorPrimaryDark = Color(0xff388E3C);
  static const Color colorAccent = Color(0xff8BC34A);
  static const Color colorPrimaryLight = Color(0xffC8E6C9);

  static const Color primaryText = Color(0xff212121);
  static const Color secondaryText = Color(0xff757575);
}

使用：selectedItemColor: CostomColors.colorPrimaryDark,