当使用 Navigator.push() 将对象从一个类传递到另一个类时，即使该对象声明为非最终对象，也不会被修改。
主屏幕:创建一个对象(userBean)并传递到第一个屏幕 第一个屏幕:显示相同的对象(userBean)值，并再次将相同的对象(userBean)传递到第二个屏幕。 第二个屏幕:尝试在第二个屏幕中修改相同的对象(userBean)，并使用refreshData.then方法在第一个屏幕中打印相同的对象(userBean)。
Main.dart
import 'package:flutter/material.dart';
import 'package:flutter_app_poc1/firstSceeen.dart';
import 'package:flutter_app_poc1/secondScreen.dart';
import 'package:flutter_app_poc1/userbean.dart';
void main() => runApp(MyApp());
typedef void refreshCallBack(int index);
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
UserBean user = new UserBean();
final List<String> hhList = ["General", "edu"];
int _counter = 0;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new FlatButton(
child: Text("Next Screen"),
onPressed: () {
user.id = 1;
user.name = "Ramesh";
Future<dynamic> refreshData =
Navigator.of(context).push(new MaterialPageRoute<dynamic>(
builder: (BuildContext context) {
return new FirstScreen(userbean: user);
},
));
refreshData.then((_) {
});
}),
],
),
),
);
}
}
Firstscreen.dart
import 'package:flutter/material.dart';
import 'package:flutter_app_poc1/secondScreen.dart';
import 'package:flutter_app_poc1/userbean.dart';
typedef void refreshCallBack(int index);
class FirstScreen extends StatefulWidget {
UserBean userbean;
FirstScreen({Key key, this.userbean}) : super(key: key);
@override
_FirstScreenState createState() => _FirstScreenState();
}
class _FirstScreenState extends State<FirstScreen> {
String userName;
final List<String> hhList = ["General", "edu"];
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("first"),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Text(widget.userbean.name),
new RaisedButton(onPressed: (){
Future<dynamic> refreshData =
Navigator.of(context).push(new MaterialPageRoute<dynamic>(
builder: (BuildContext context) {
return new SecondScreen(userbean: widget.userbean);
},
));
refreshData.then((_) {
print(widget.userbean.name);
});
}),
],
),
),
);
}
}
secondscreen.dart
import 'package:flutter/material.dart';
import 'package:flutter_app_poc1/userbean.dart';
class SecondScreen extends StatefulWidget {
UserBean userbean;
SecondScreen({Key key, this.userbean}) : super(key: key);
@override
_SecondScreenState createState() => _SecondScreenState();
}
class _SecondScreenState extends State<SecondScreen> {
UserBean bean = UserBean();
@override
Widget build(BuildContext context) {
bean.name = "suresh";
return Scaffold(
appBar: AppBar(
title: Text("Previous Screen"),
),
body: Center(
child: new FlatButton(
child: Text(bean.name),
onPressed: () {
print(bean.name);
widget.userbean = bean;
Navigator.pop(context, true);
}),
));
}
}
最佳答案
@Murali
如果您想遵循相同的过程传递对象，请遵循以下过程。
从 Navigator.pop 再次推送新对象
onPressed: () {
print("TEST second screen :"+bean.name);
/// here modifying with new object.
widget.userbean = bean;
Navigator.pop(context, widget.userbean);
}),
在第二个屏幕中，从功能方法获取新对象，如下所示
Future<UserBean> refreshData =
Navigator.of(context).push(new MaterialPageRoute<UserBean>(
builder: (BuildContext context) {
return new SecondScreen(userbean: widget.userbean);
},
));
refreshData.then((res) {
print("TEST First screen : ${res.name}");
});
然后对象将更改为新值。
关于Flutter navigator.push() 对象问题，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/53652948/