About 6 months ago, the code was working just fine, and then this exception occurred. i don't know what to do about it because I tried to fix it by making it nullable but it didn't work So what should I do? the code is a bottom navigation bar this is a picture of the exception :

the code :

    import 'package:blackboard/view/Teacher/AddSheetTeacher.dart';
import 'package:blackboard/view/Teacher/CoursesTeacher.dart';
import 'package:blackboard/view/Teacher/HSTeacher.dart';
import 'package:blackboard/view/Teacher/CoursesTeacher1.dart';
import 'package:flutter/material.dart';
import 'package:blackboard/view/Teacher/HomeScreenTeacher.dart';
import 'package:blackboard/view/Teacher/YourCoursesTeacher.dart';
import 'package:blackboard/view/Teacher/ProfileTeacher.dart';

class dashboard extends StatefulWidget {
  @override
  State<dashboard> createState() => _dashboardState();
}

class _dashboardState extends State<dashboard> {
  int _currentIndex = 0;
  List screens = [CoursesT, HomeScreenTeacher(), HomeScreen()];

  void _updateIndex(int value) {
    setState(() {
      _currentIndex = value;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: screens[_currentIndex],
      bottomNavigationBar: BottomNavigationBar(
        backgroundColor: Colors.transparent,
        elevation: 0,
        type: BottomNavigationBarType.fixed,
        currentIndex: _currentIndex,
        onTap: (_updateIndex),
        selectedItemColor: Colors.purple.shade700,
        selectedFontSize: 13,
        unselectedFontSize: 13,
        iconSize: 30,
        items: [
          BottomNavigationBarItem(
            label: "HomeScreen",
            icon: Icon(
              Icons.home,
              size: 30,
            ),
          ),
          BottomNavigationBarItem(
            label: "Course",
            icon: Icon(
              Icons.book,
              size: 30,
            ),
          ),
          BottomNavigationBarItem(
            label: "Profile",
            icon: Icon(
              Icons.account_box,
              size: 30,
            ),
          ),
        ],
      ),
    );
  }
}

CodePudding user response：

Mention the type of the list List<Widget>

List screens = [CoursesT, HomeScreenTeacher(), HomeScreen()];

to

List<Widget> screens = [CoursesT, HomeScreenTeacher(), HomeScreen()];

CodePudding user response：

The issue is here on CoursesT which is need to be CoursesT() inside screens.

List<Widget> screens = [CoursesT(), HomeScreenTeacher(), HomeScreen()];