那些遇到过的问题

无法构建，因为框架已经在构建 - Flutter

Gok*_*oku 2 android dart flutter flutter-layout

我想AlertDialog在点击抽屉项目时显示

我使用下面的代码在我的 flutter 应用程序中使用导航抽屉项目

class HomePage extends StatefulWidget {
  final drawerItems = [
    DrawerItem("View Your account", Icons.account_circle),
    DrawerItem("Request", Icons.receipt),
    DrawerItem("Order", Icons.shopping_cart),
    DrawerItem("Report", Icons.report_problem),
    DrawerItem("Log out", Icons.info)
  ];

  @override
  State<StatefulWidget> createState() {
    return new HomePageState();
  }
}

class HomePageState extends State<HomePage> {
  int _selectedDrawerIndex = 0;
  bool visibilityTag = false;

  showAlertDialog(BuildContext context) {
    // set up the button
    Widget okButton = FlatButton(
      child: Text("OK"),
      onPressed: () {
        Navigator.of(context).pop();
      },
    );
    Widget cancelButton = FlatButton(
      child: Text("Cancel"),
      onPressed: () {
        Navigator.of(context).pop();
      },
    );

    // set up the AlertDialog
    AlertDialog alert = AlertDialog(
      elevation: 10,
      shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.all(Radius.circular(20.0))),
      title: Text("ORICON"),
      content: Column(
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          Text("Are you sure you want to logout?"),
          Padding(
            padding: const EdgeInsets.only(top: 20.0),
            child: Text(
              "1300 898 989",
              style: TextStyle(
                  color: Colors.blue,
                  fontWeight: FontWeight.bold,
                  fontSize: 20.0),
            ),
          ),
        ],
      ),
      actions: [okButton, cancelButton],
    );

    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (BuildContext context) {
        return alert;
      },
    );
  }

  _getDrawerItemWidget(int pos) {
    switch (pos) {
      case 0:
        visibilityTag = false;
        return AccountDetails();
      case 1:
        visibilityTag = true;
        return RequestBin();
      case 2:
        visibilityTag = true;
        return OrderBin();
      case 3:
        visibilityTag = true;
        return Report();
      case 4:
        showAlertDialog(context);
        visibilityTag = false;
        return AccountDetails();
      default:
        return new Text("Error");
    }
  }

  _onSelectItem(int index) {
    if (index == 0) {
      visibilityTag = false;
    } else {
      visibilityTag = true;
    }
//    setState(() => _selectedDrawerIndex = index);
    _selectedDrawerIndex = index; // removed setState call
    Navigator.of(context).pop(); // close the drawer
  }

  @override
  Widget build(BuildContext context) {
    List<Widget> drawerOptions = [];
    for (var i = 0; i < widget.drawerItems.length; i++) {
      var d = widget.drawerItems[i];
      drawerOptions.add(new ListTile(
        leading: Icon(d.icon),
        title: Text(d.title),
        selected: i == _selectedDrawerIndex,
        onTap: () => _onSelectItem(i),
      ));
    }

    Future<bool> customPop() {
      if (_selectedDrawerIndex == 0) {
        visibilityTag = false;
        return Future.value(true);
      } else {
        setState(() {
          visibilityTag = false;
          _selectedDrawerIndex = 0;
        });
        return Future.value(false);
      }
    }

    void navigateToHomeScreen() {
      if (_selectedDrawerIndex == 0) {
        visibilityTag = false;
      } else {
        visibilityTag = false;
        setState(() {
          _selectedDrawerIndex = 0;
        });
      }
    }

    return WillPopScope(
      onWillPop: customPop,
      child: Scaffold(
          appBar: AppBar(
            backgroundColor: Colors.white,
            iconTheme: IconThemeData(color: Colors.black), //add this line here
            // here we display the title corresponding to the fragment
            // you can instead choose to have a static title
            title: Text(
              widget.drawerItems[_selectedDrawerIndex].title,
              style: TextStyle(color: Colors.black),
            ),
            actions: <Widget>[
              Padding(
                padding: const EdgeInsets.only(right: 10),
                child: Visibility(
                    visible: visibilityTag,
                    child: Row(
                      children: <Widget>[
                        IconButton(
                          icon: new Icon(Icons.arrow_back_ios),
                          color: Colors.grey,
                          onPressed: navigateToHomeScreen,
                        ),
                        Text(
                          "BACK",
                          style: TextStyle(color: Colors.grey),
                        )
                      ],
                    )),
              )
            ],
          ),
          drawer: Drawer(
            child: Column(
              children: <Widget>[
                UserAccountsDrawerHeader(
                    accountName: new Text("Nilesh Rathod"), accountEmail: null),
                Column(children: drawerOptions)
              ],
            ),
          ),
          body: _getDrawerItemWidget(_selectedDrawerIndex)),
    );
  }
}
Run Code Online (Sandbox Code Playgroud)

但我低于例外

This Overlay widget cannot be marked as needing to build because the framework is already in the process of building widgets.  A widget can be marked as needing to be built during the build phase only if one of its ancestors is currently building. This exception is allowed because the framework builds parent widgets before children, which means a dirty descendant will always be built. Otherwise, the framework might not visit this widget during this build phase.
The widget on which setState() or markNeedsBuild() was called was: Overlay-[LabeledGlobalKey<OverlayState>#7e1a8]
  state: OverlayState#72b8b(entries: [OverlayEntry#cf40a(opaque: false; maintainState: false), OverlayEntry#e10aa(opaque: false; maintainState: true), OverlayEntry#e0ccc(opaque: false; maintainState: false), OverlayEntry#5fdab(opaque: false; maintainState: true)])
The widget which was currently being built when the offending call was made was: HomePage
  dirty
  dependencies: [_InheritedTheme, _LocalizationsScope-[GlobalKey#c84d4]]
  state: HomePageState#982b0
User-created ancestor of the error-causing widget was: 
  MaterialApp file:///home/ctpl119/Documents/NEW_PROJECT/oricon/oricon/lib/main.dart:11:10
When the exception was thrown, this was the stack: 
#0      Element.markNeedsBuild.<anonymous closure> (package:flutter/src/widgets/framework.dart:3687:11)
#1      Element.markNeedsBuild (package:flutter/src/widgets/framework.dart:3702:6)
#2      State.setState (package:flutter/src/widgets/framework.dart:1161:14)
#3      OverlayState.insertAll (package:flutter/src/widgets/overlay.dart:346:5)
#4      OverlayRoute.install (package:flutter/src/widgets/routes.dart:43:24)
Run Code Online (Sandbox Code Playgroud)

我已经检查过下面的堆栈溢出链接

如果需要更多信息，请告诉我。提前致谢。您的努力将受到赞赏。

chu*_*han 10

您可以复制粘贴运行下面的完整代码
您需要WidgetsBinding.instance.addPostFrameCallback

代码片段

case 4:
        //showAlertDialog(context);
        WidgetsBinding.instance.addPostFrameCallback((_) {
          showAlertDialog(context);
        });
        visibilityTag = false;
        return AccountDetails();
Run Code Online (Sandbox Code Playgroud)

工作演示

在此输入图像描述

完整代码

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: HomePage(),
    );
  }
}

class DrawerItem {
  String title;
  IconData icon;

  DrawerItem(this.title, this.icon);
}

class HomePage extends StatefulWidget {
  final drawerItems = [
    DrawerItem("View Your account", Icons.account_circle),
    DrawerItem("Request", Icons.receipt),
    DrawerItem("Order", Icons.shopping_cart),
    DrawerItem("Report", Icons.report_problem),
    DrawerItem("Log out", Icons.info)
  ];

  @override
  State<StatefulWidget> createState() {
    return new HomePageState();
  }
}

class HomePageState extends State<HomePage> {
  int _selectedDrawerIndex = 0;
  bool visibilityTag = false;

  showAlertDialog(BuildContext context) {
    // set up the button
    Widget okButton = FlatButton(
      child: Text("OK"),
      onPressed: () {
        Navigator.of(context).pop();
      },
    );
    Widget cancelButton = FlatButton(
      child: Text("Cancel"),
      onPressed: () {
        Navigator.of(context).pop();
      },
    );

    // set up the AlertDialog
    AlertDialog alert = AlertDialog(
      elevation: 10,
      shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.all(Radius.circular(20.0))),
      title: Text("ORICON"),
      content: Column(
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          Text("Are you sure you want to logout?"),
          Padding(
            padding: const EdgeInsets.only(top: 20.0),
            child: Text(
              "1300 898 989",
              style: TextStyle(
                  color: Colors.blue,
                  fontWeight: FontWeight.bold,
                  fontSize: 20.0),
            ),
          ),
        ],
      ),
      actions: [okButton, cancelButton],
    );

    showDialog(
      context: context,
      barrierDismissible: false,
      builder: (BuildContext context) {
        return alert;
      },
    );
  }

  _getDrawerItemWidget(int pos) {
    switch (pos) {
      case 0:
        visibilityTag = false;
        return AccountDetails();
      case 1:
        visibilityTag = true;
        return RequestBin();
      case 2:
        visibilityTag = true;
        return OrderBin();
      case 3:
        visibilityTag = true;
        return Report();
      case 4:
        //showAlertDialog(context);
        WidgetsBinding.instance.addPostFrameCallback((_) {
          showAlertDialog(context);
        });
        visibilityTag = false;
        return AccountDetails();
      default:
        return new Text("Error");
    }
  }

  _onSelectItem(int index) {
    if (index == 0) {
      visibilityTag = false;
    } else {
      visibilityTag = true;
    }
    setState(() => _selectedDrawerIndex = index);
    //_selectedDrawerIndex = index; // removed setState call
    Navigator.of(context).pop(); // close the drawer
  }

  @override
  Widget build(BuildContext context) {
    List<Widget> drawerOptions = [];
    for (var i = 0; i < widget.drawerItems.length; i++) {
      var d = widget.drawerItems[i];
      drawerOptions.add(new ListTile(
        leading: Icon(d.icon),
        title: Text(d.title),
        selected: i == _selectedDrawerIndex,
        onTap: () => _onSelectItem(i),
      ));
    }

    Future<bool> customPop() {
      if (_selectedDrawerIndex == 0) {
        visibilityTag = false;
        return Future.value(true);
      } else {
        setState(() {
          visibilityTag = false;
          _selectedDrawerIndex = 0;
        });
        return Future.value(false);
      }
    }

    void navigateToHomeScreen() {
      if (_selectedDrawerIndex == 0) {
        visibilityTag = false;
      } else {
        visibilityTag = false;
        setState(() {
          _selectedDrawerIndex = 0;
        });
      }
    }

    return WillPopScope(
      onWillPop: customPop,
      child: Scaffold(
          appBar: AppBar(
            backgroundColor: Colors.white,
            iconTheme: IconThemeData(color: Colors.black), //add this line here
            // here we display the title corresponding to the fragment
            // you can instead choose to have a static title
            title: Text(
              widget.drawerItems[_selectedDrawerIndex].title,
              style: TextStyle(color: Colors.black),
            ),
            actions: <Widget>[
              Padding(
                padding: const EdgeInsets.only(right: 10),
                child: Visibility(
                    visible: visibilityTag,
                    child: Row(
                      children: <Widget>[
                        IconButton(
                          icon: new Icon(Icons.arrow_back_ios),
                          color: Colors.grey,
                          onPressed: navigateToHomeScreen,
                        ),
                        Text(
                          "BACK",
                          style: TextStyle(color: Colors.grey),
                        )
                      ],
                    )),
              )
            ],
          ),
          drawer: Drawer(
            child: Column(
              children: <Widget>[
                UserAccountsDrawerHeader(
                    accountName: new Text("Nilesh Rathod"), accountEmail: null),
                Column(children: drawerOptions)
              ],
            ),
          ),
          body: _getDrawerItemWidget(_selectedDrawerIndex)),
    );
  }
}

class AccountDetails extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("AccountDetails");
  }
}

class RequestBin extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("RequestBin");
  }
}

class OrderBin extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("OrderBin");
  }
}

class Report extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("Report");
  }
}
Run Code Online (Sandbox Code Playgroud)

归档时间：

查看次数：

3608 次

最近记录：

5 年，10 月 前
颤抖 - 无法建造,因为frawework已经建成 10
Flutter 错误：“Widget 无法构建，因为已经在构建过程中” 5
在Flutter中添加OverlayEntry 3
更多相关链接
相关归档
我如何adb拉出SD卡中存在的文件夹的所有文件 103
Android Ice Cream Sandwich Edittext:禁用拼写检查和自动换行 43
“你的 flutter checkout 有本地更改，升级后这些更改会被删除。” 运行 flutter 升级时 20
在Android上的Flutter应用程序中是否有任何方法拦截'Back'keydown？ 10
用Dart解析JSON 8
Flutter，BLoC 需要 rx dart 吗？ 7
我如何从库比蒂诺日期选择器中隐藏一天 5
如何在flutter中将sqlite db导出到googledrive 5
颤振异步验证表单 3
dart中生成的代码的可读性 2
难疑归档
如何将Git存储库还原为以前的提交 7278
可以在JSON中使用注释吗？ 7104
如何删除子模块？ 3366
我应该在MySQL中使用日期时间或时间戳数据类型吗？ 2598
如何使用Maven创建具有依赖关系的可执行JAR？ 2276
Dockerfile中的`COPY`和`ADD`命令有什么区别？ 1991
lodash和下划线之间的差异 1566
如何将分离的HEAD与master/origin协调？ 1506
如何在Javascript中的数组开头添加新的数组元素？ 1476
在关系数据库中存储分层数据有哪些选项？ 1281