Flutter flatter navigator.push()对象问题
使用Navigator.push()将对象从一个类传递到另一个类时,该对象即使声明为非final也不会得到修改 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)传递给第二个屏幕。 第二屏:尝试在第二屏中获取修改相同对象(userBean),并使用refreshData.then方法在第一屏中打印相同对象(userBean)Flutter flatter navigator.push()对象问题,flutter,flutter-dependencies,Flutter,Flutter Dependencies,使用Navigator.push()将对象从一个类传递到另一个类时,该对象即使声明为非final也不会得到修改 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)传递给第二个屏幕。 第二屏:尝试在第二屏中获取修改相同对象(userBean),并使用refreshData.then方法在第一屏中打印相同对象(userBean) Main.dart import 'package:flutter/mat
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);
}),
));
}
}
Main.dart
进口“包装:颤振/材料.省道”;
导入“包:颤振应用程序poc1/FirstSceen.dart”;
导入“包:flatter_app_poc1/secondScreen.dart”;
导入“包:flatter_app_poc1/userbean.dart”;
void main()=>runApp(MyApp());
typedef无效刷新回调(int索引);
类MyApp扩展了无状态小部件{
//此小部件是应用程序的根。
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主题:主题数据(
主样本:颜色。蓝色,
),
主页:MyHomePage(标题:“颤振演示主页”),
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage({Key,this.title}):超级(Key:Key);
最后的字符串标题;
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
UserBean user=newuserbean();
最终列表hhList=[“一般”、“教育单元”];
int _计数器=0;
@凌驾
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(
标题:文本(widget.title),
),
正文:中(
子:列(
mainAxisAlignment:mainAxisAlignment.center,
儿童:[
新扁平按钮(
子:文本(“下一屏幕”),
已按下:(){
user.id=1;
user.name=“Ramesh”;
未来刷新数据=
导航器.of(上下文).push(新材料路线)(
生成器:(BuildContext上下文){
返回新的FirstScreen(userbean:user);
},
));
刷新数据。然后(){
});
}),
],
),
),
);
}
}
第一屏,飞镖
进口“包装:颤振/材料.省道”;
导入“包:flatter_app_poc1/secondScreen.dart”;
导入“包:flatter_app_poc1/userbean.dart”;
typedef无效刷新回调(int索引);
类FirstScreen扩展StatefulWidget{
用户bean用户bean;
FirstScreen({Key-Key,this.userbean}):super(Key:Key);
@凌驾
_FirstScreenState createState()=>\u FirstScreenState();
}
类_FirstScreenState扩展了状态{
字符串用户名;
最终列表hhList=[“一般”、“教育单元”];
@凌驾
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(
标题:正文(“第一”),
),
正文:中(
子:列(
mainAxisAlignment:mainAxisAlignment.center,
儿童:[
新文本(widget.userbean.name),
新升起按钮(按下时:(){
未来刷新数据=
导航器.of(上下文).push(新材料路线)(
生成器:(BuildContext上下文){
返回新的SecondScreen(userbean:widget.userbean);
},
));
刷新数据。然后(){
打印(widget.userbean.name);
});
}),
],
),
),
);
}
}
飞镖
进口“包装:颤振/材料.省道”;
导入“包:flatter_app_poc1/userbean.dart”;
类SecondScreen扩展StatefulWidget{
用户bean用户bean;
SecondScreen({Key-Key,this.userbean}):super(Key:Key);
@凌驾
_SecondScreenState createState()=>\u SecondScreenState();
}
类_SecondScreenState扩展状态{
UserBean=UserBean();
@凌驾
小部件构建(构建上下文){
bean.name=“suresh”;
返回脚手架(
appBar:appBar(
标题:文本(“上一屏幕”),
),
正文:中(
孩子:新的扁平按钮(
子:文本(bean.name),
已按下:(){
打印(bean.name);
widget.userbean=bean;
pop(上下文,true);
}),
));
}
}
@Murali
如果要执行相同的过程传递对象,请执行以下过程
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,从特征方法获取新对象,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 : ${res.name}");
});
未来刷新数据=
导航器.of(上下文).push(新材料路线)(
生成器:(BuildContext上下文){
返回新的SecondScreen(userbean:widget.userbean);
},
));
刷新数据。然后((res){
打印(“测试第一屏:${res.name}”);
});
然后对象将使用新值进行更改。每个类都会为对象userBean创建一个新引用-您只需将数据从对象的一个引用传递到对象userBean的另一个引用。修改第三类对象数据不会影响第一类对象数据,因为它们在内存中都有单独的指针。