Navigator.pop(context) 显示空白

Question

我试图使用 Navigator.pop(context) 导航回第一个屏幕，但它显示的是空白屏幕，而不是返回到第一个屏幕。我该如何解决这个问题

主屏幕

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:font_awesome_flutter/font_awesome_flutter.dart';
import 'GenderButton.dart';
import 'constants.dart';
import 'buttons.dart';
import 'resultpage.dart';

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Center(child: Text('')),
          elevation: 0,
          actions: [
            IconButton(
                onPressed: () {},
                icon: Icon(
                  Icons.add_alert_sharp,
                  size: 35,
                ))
          ],
          leading: IconButton(
            onPressed: () {},
            icon: Icon(
              Icons.add,
              size: 35,
            ),
          ),
        ),
        body: HomeScreen());
  }
}

class HomeScreen extends StatefulWidget {
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  Gender SelectedGender = Gender.empty;
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        //BMI Calculator Header
        Row(
          children: [
            SizedBox(
              width: 30,
            ),
            Text(
              'BMI Calculator',
              style: TextStyle(fontSize: 30, fontWeight: FontWeight.bold),
            ),
          ],
        ),
        SizedBox(
          height: 20,
        ),
        //Gender Text
        Row(
          children: [
            SizedBox(
              width: 25,
            ),
            Text(
              'Gender',
              style: TextStyle(fontSize: 17),
            ),
          ],
        ),
        SizedBox(
          height: 10,
        ),
        //Button Widget
        Row(
          children: [
            SizedBox(
              width: 25,
            ),
            BoxButton(
              Type: 'MALE',
              BorderColor: SelectedGender == Gender.male
                  ? activeCardColor
                  : inactiveCardColor,
              IconColor:
                  SelectedGender == Gender.male ? activeCardColor : inactiv,
              OnPress: () {
                setState(() {
                  SelectedGender = Gender.male;
                });
              },
            ),
            SizedBox(
              width: 15,
            ),
            BoxButton(
              Type: 'FEMALE',
              BorderColor: SelectedGender == Gender.female
                  ? activeCardColor
                  : inactiveCardColor,
              IconColor:
                  SelectedGender == Gender.female ? activeCardColor : inactiv,
              OnPress: () {
                setState(() {
                  SelectedGender = Gender.female;
                });
              },
            ),
          ],
        ),
        SizedBox(
          height: 20,
        ),
        //Weight Text
        Row(
          children: [
            SizedBox(
              width: 25,
            ),
            //Weight Text
            Text(
              'Weight',
              style: TextStyle(fontSize: 15),
            )
          ],
        ),
        SizedBox(
          height: 5,
        ),
        Row(
          children: [
            SizedBox(
              width: 25,
            ),
            Container(
              decoration: BoxDecoration(
                  color: Colors.white, borderRadius: BorderRadius.circular(8)),
              // margin: EdgeInsets.all(15),
              height: 50,
              width: 250,
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: [
                  RoundedIconButton(
                    icon: FontAwesomeIcons.minus,
                    onPressed: () {
                      setState(() {
                        Weight--;
                      });
                    },
                  ),
                  SizedBox(
                    width: 55,
                  ),
                  Text(
                    Weight.toString(),
                    style: TextStyle(
                        color: Colors.black,
                        fontSize: 20,
                        fontWeight: FontWeight.bold),
                  ),
                  SizedBox(
                    width: 50,
                  ),
                  RoundedIconButton(
                    icon: FontAwesomeIcons.plus,
                    onPressed: () {
                      setState(() {
                        Weight++;
                      });
                    },
                  )
                ],
              ),
            ),
            SizedBox(
              width: 10,
            ),
            Container(
              height: 50,
              width: 100,
              decoration: BoxDecoration(
                  color: Colors.white, borderRadius: BorderRadius.circular(9)),
            )
          ],
        ),
        SizedBox(
          height: 20,
        ),
        //Height Text
        Row(
          children: [
            SizedBox(
              width: 25,
            ),
            Text(
              'Height',
              style: TextStyle(fontSize: 15),
            )
          ],
        ),
        Row(
          children: [
            SizedBox(
              width: 25,
            ),
            Container(
              decoration: BoxDecoration(
                  color: Colors.white, borderRadius: BorderRadius.circular(8)),
              // margin: EdgeInsets.all(15),
              height: 50,
              width: 250,
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: [
                  RoundedIconButton(
                    icon: FontAwesomeIcons.minus,
                    onPressed: () {
                      setState(() {
                        Height--;
                      });
                    },
                  ),
                  SizedBox(
                    width: 55,
                  ),
                  Text(
                    Height.toString(),
                    style: TextStyle(
                        color: Colors.black,
                        fontSize: 20,
                        fontWeight: FontWeight.bold),
                  ),
                  SizedBox(
                    width: 50,
                  ),
                  RoundedIconButton(
                    icon: FontAwesomeIcons.plus,
                    onPressed: () {
                      setState(() {
                        Height++;
                      });
                    },
                  )
                ],
              ),
            ),
            SizedBox(
              width: 10,
            ),
            Container(
              height: 50,
              width: 100,
              decoration: BoxDecoration(
                  color: Colors.white, borderRadius: BorderRadius.circular(9)),
            )
          ],
        ),
        SizedBox(
          height: 20,
        ),
        Row(
          children: [
            SizedBox(
              width: 25,
            ),
            Text(
              'Age',
              style: TextStyle(fontSize: 18),
            )
          ],
        ),
        SizedBox(
          height: 5,
        ),
        Container(
          decoration: BoxDecoration(
              color: Colors.white, borderRadius: BorderRadius.circular(8)),
          height: 50,
          width: 369,
          child: Container(
            // margin: EdgeInsets.all(15),
            height: 50,
            width: 250,
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
              children: [
                RoundedIconButton(
                  icon: FontAwesomeIcons.minus,
                  onPressed: () {
                    setState(() {
                      Age--;
                    });
                  },
                ),
                SizedBox(
                  width: 100,
                ),
                Text(
                  Age.toString(),
                  style: TextStyle(
                      color: Colors.black,
                      fontSize: 20,
                      fontWeight: FontWeight.bold),
                ),
                SizedBox(
                  width: 110,
                ),
                RoundedIconButton(
                  icon: FontAwesomeIcons.plus,
                  onPressed: () {
                    setState(() {
                      Age++;
                    });
                  },
                )
              ],
            ),
          ),
        ),
        SizedBox(
          height: 20,
        ),
        GestureDetector(
          onTap: () {
            Navigator.push(context, MaterialPageRoute(builder: (context) {
              return ResultPage();
            }));
          },
          child: Container(
            decoration: BoxDecoration(
                color: Color(0xFF06C46C),
                borderRadius: BorderRadius.circular(8)),
            height: 50,
            width: 369,
            child: Center(
                child: Text(
              'Calculate',
              style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold),
            )),
          ),
        ),
      ],
    );
  }
}

屏幕 2

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

class ResultPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(
          scaffoldBackgroundColor: Colors.black,
          textTheme: TextTheme(
            bodyText2: TextStyle(color: Colors.white),
          ),
          colorScheme: ColorScheme.light(
              primary: Colors.black, secondary: Colors.black)),
      home: Scaffold(
          appBar: AppBar(
            title: Center(child: Text('')),
            elevation: 0,
            actions: [
              IconButton(
                  onPressed: () {},
                  icon: Icon(
                    Icons.add_alert_sharp,
                    size: 35,
                  ))
            ],
            leading: IconButton(
              onPressed: () {},
              icon: Icon(
                Icons.add,
                size: 35,
              ),
            ),
          ),
          body: Results()),
    );
  }
}

class Results extends StatefulWidget {
  @override
  _ResultsState createState() => _ResultsState();
}

class _ResultsState extends State<Results> {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Text(
            'Result',
            style: TextStyle(fontSize: 30),
          ),
          Center(
            child: Container(
              decoration: BoxDecoration(
                  color: Color(0xFF333335),
                  borderRadius: BorderRadius.circular(8)),
              margin: EdgeInsets.all(10),
              height: 300,
              width: 350,
            ),
          ),
          Center(
            child: Container(
              margin: EdgeInsets.all(35),
              child: Text('For your height , a normal would be from 48.6 '
                  'to 63.3 kilograms'),
            ),
          ),
          GestureDetector(
            onTap: () {
              Navigator.pop(context);
            },
            child: Container(
              decoration: BoxDecoration(
                  color: Color(0xFF06C46C),
                  borderRadius: BorderRadius.circular(8)),
              height: 50,
              width: 369,
              child: Center(
                  child: Text(
                'Recalculate BMI',
                style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold),
              )),
            ),
          ),
        ],
      ),
    );
  }
}

而且如果你看看我如何定位我的所有小部件以获得与我在运球上看到的设计相同的样式 enter link description here 做得对吗？因为我觉得我做错了，而且我还是个初学者，我正试图重现我从在 udemy 上购买的课程中学到的东西？

Answer 1

试试下面的代码希望对你有帮助。设置 rootNavigator: true

参考导航here , here, here

   Navigator.of(
        context,
        rootNavigator: true,
      ).pop(
        context,
      );

或尝试以下解决方案

Navigator.pop(context);

完整代码：

import 'package:flutter/material.dart';

void main() {
  runApp(const MaterialApp(
    title: 'Navigation Basics',
    home: FirstRoute(),
  ));
}

class FirstRoute extends StatelessWidget {
  const FirstRoute({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('First Route'),
      ),
      body: Center(
        child: ElevatedButton(
          child: const Text('Open route'),
          onPressed: () {
            Navigator.push(
              context,
              MaterialPageRoute(builder: (context) => const SecondRoute()),
            );
          },
        ),
      ),
    );
  }
}


class SecondRoute extends StatefulWidget {
  const SecondRoute({Key? key}) : super(key: key);

  @override
  State<SecondRoute> createState() => _SecondRouteState();
}

class _SecondRouteState extends State<SecondRoute> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Second Route"),
      ),
      body: Center(
        child: ElevatedButton(
          onPressed: () {
            Navigator.pop(context);
          },
          child: const Text('Go back!'),
        ),
      ),
    );
  }
}

测试此代码here

Navigator.pop(context) 显示空白

Navigator.pop(context) showing blank

navigation

dart

flutter

flutter-layout

flutter-animation