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Flutter 实例&x27;小部件';can';不能在初始值设定项中访问_Flutter - Fatal编程技术网

Flutter 实例&x27;小部件';can';不能在初始值设定项中访问

Flutter 实例&x27;小部件';can';不能在初始值设定项中访问,flutter,Flutter,我在访问菜单ScreenState上的变量用户时遇到问题: class MenuScreen extends StatefulWidget { final User user; MenuScreen(this.user); @override _MenuScreenState createState() => _MenuScreenState(); } class _MenuScreenState extends State<MenuScreen> {

我在访问菜单ScreenState上的变量用户时遇到问题:

class MenuScreen extends StatefulWidget {
  final User user;
  
  MenuScreen(this.user);
  @override
  _MenuScreenState createState() => _MenuScreenState();
}

class _MenuScreenState extends State<MenuScreen> {
  final User userInMenu = widget.user;
}
class MenuScreen扩展StatefulWidget{
最终用户;
菜单屏幕(this.user);
@凌驾
_MenuScreenState createState()=>\u MenuScreenState();
}
类_菜单ScreenState扩展状态{
最终用户userInMenu=widget.User;
}
显示的问题是“无法在初始值设定项中访问实例成员'widget'。
尝试用不同的表达式替换对实例成员的引用。“

您必须在initState中执行此操作,如下所示:

class MenuScreen扩展StatefulWidget{
最终用户;
菜单屏幕(this.user);
@凌驾
_MenuScreenState createState()=>\u MenuScreenState();
}
类_菜单ScreenState扩展状态{
User userInMenu=widget.User;
@凌驾
void initState(){
super.initState();
userInMenu=widget.user;
}

如果我的回答对你有帮助,请将其更新,以便其他人也能理解。谢谢

小部件中的问题已经解决,但在“用户”类中,我有一个列表,需要复制他。当我复制这些数据时,同样的问题也会发生。最终列表_plants=List.from(userInMenu(此处)。userPlantList)'无法在初始值设定项中访问实例成员'userInMenu'。obs:我有一些方法可以添加和删除列表中的元素。