Flutter 使用 GlobalKey 从另一个类更改状态

Posted 2023-02-23

【中文标题】Flutter 使用 GlobalKey 从另一个类更改状态

【英文标题】：Flutter change state from another class using GlobalKey

【发布时间】：2020-05-18 18:44:30

【问题描述】：

我有一个底页，它有可以更改的子项。我正在尝试使用GlobalKey 从孩子那里访问父母的方法。它在下面抛出异常：

The following NoSuchMethodError was thrown while handling a gesture:
The method 'selectedChild' was called on null.
Receiver: null
Tried calling: selectedChild(1)

我只是想改变另一个类的状态。任何建议都会很棒。我怎样才能让它发挥作用？

家长：

class _ServicesModal extends StatefulWidget 
  @override
  ServicesModalState createState() => ServicesModalState();


class ServicesModalState extends State<_ServicesModal> 
  var selectedChild = 0;
  var _children = [
    ServicePackage(),
    Calls()
  ];

  selectChildren(int select) 
    setState(() 
      selectedChild = select;
    );
  

  @override
  Widget build(BuildContext context) 
    return Container(
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.only(
          topLeft: Radius.circular(20),
          topRight: Radius.circular(20),
        )
      ),
      child: ClipRRect(
        borderRadius: BorderRadius.only(
          topLeft: Radius.circular(20),
          topRight: Radius.circular(20),
        ),
        child: _children[selectedChild]
      ),
    );
  

孩子：

class ServicePackage extends StatefulWidget 

  GlobalKey<ServicesModalState> _serviceModalState = GlobalKey();

  @override
  _ServicePackageState createState() => _ServicePackageState();


class _ServicePackageState extends State<ServicePackage> 
  @override
  Widget build(BuildContext context) 
    return Container(
      child: IconButton(
        icon: Icon(Icons.add),
        onPressed: () 
         setState(() 
           widget._serviceModalState.currentState.selectedChild(1);
         );
        ,
      ),
    );
  

【问题讨论】：

检查这个答案可能会有所帮助***.com/a/56928670/10660823

【参考方案1】：

您在 _ServicePackageState 类中将 selectChildren 错误地输入为 selectedChild。