why it doesn't work,it worked fine in without null safety something might be missed. but i dont understand what's wrong It would be greate help if you give some time to this
// ignore_for_file: prefer_const_constructors, sized_box_for_whitespace, use_key_in_widget_constructors,prefer_const_literals_to_create_immutables
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:http/http.dart' show get;
import 'dart:convert';
class Homes {
final String id;
final String name, addr, image_url, desciption;
final String price;
Homes({
this.id='',
this.name='',
this.addr='',
this.image_url='',
this.desciption='',
this.price='',
});
factory Homes.fromJson(Map<String, dynamic> jsonData) {
return Homes(
id: jsonData['id'],
name: jsonData['name'],
addr: jsonData['addr'],
desciption: jsonData['desciption'],
// http://192.168.0.106/flutter/
image_url: "https://homeshouse.000webhostapp.com/images/" jsonData['image_url'],
price: jsonData['price'],
);
}
}
class CustomListView extends StatelessWidget {
final List<Homes> homelist;
CustomListView(this.homelist);
Widget build(context) {
return ListView.builder(
itemCount: homelist.length,
itemBuilder: (context, int currentIndex) {
return createViewItem(homelist[currentIndex], context);
},
);
}
Widget createViewItem(Homes homelist, BuildContext context) {
// ignore: unnecessary_new
return new Padding(
padding: const EdgeInsets.symmetric(horizontal: 20.0),
child: Container(
margin: EdgeInsets.only(top: 10), //hotel container
height: 165,
width: double.infinity,
// width: 10,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(10.0),
color: Colors.white,
boxShadow: [
BoxShadow(
color: Colors.black12,
offset: Offset(0.0, 4.0),
blurRadius: 10.0,
)
],
),
child: Stack(
children: <Widget>[
Positioned(
child: Container(
height: 140,
width: 135,
decoration: BoxDecoration(
borderRadius: BorderRadius.only(
topLeft: Radius.circular(10.0),
bottomLeft: Radius.circular(10.0),
),
image: DecorationImage(
image: NetworkImage(homelist.image_url),
fit: BoxFit.cover,
),
),
),
),
Positioned(
top: 5,
left: 150, //EDTIED
right: 20,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Text(
'${homelist.name}',
style: TextStyle(
fontSize: 18.0,
fontWeight: FontWeight.w400,
),
),
SizedBox(
height: 5,
),
Text(
'${homelist.desciption}',
style: TextStyle(
fontSize: 14.0,
color: Colors.grey,
),
),
SizedBox(height: 5),
Text(
'${homelist.addr}',
style: TextStyle(
fontSize: 14.0,
color: Colors.grey,
),
),
SizedBox(height: 5),
Text(
// '\$${hotels[index].price} / night',
'${homelist.price} / nigth',
style: TextStyle(fontSize: 16, color: Colors.teal),
),
Padding(
padding: const EdgeInsets.only(left: 2, top: 10),
child: Row(
children: <Widget>[
Icon(
Icons.directions_car,
color: Colors.orange.shade300,
),
SizedBox(
width: 10,
),
// Icon(
// Icons.hot_tub,
// color: Colors.blue,
// ),
// SizedBox(
// width: 10,
// ),
Icon(
Icons.fastfood_rounded,
color: Colors.orange.shade300,
),
SizedBox(
width: 10,
),
Icon(
Icons.wifi,
color: Colors.orange.shade300,
),
SizedBox(
width: 15.0,
),
ElevatedButton(onPressed: () {
//We start by creating a Page Route.
//A MaterialPageRoute is a modal route that replaces the entire
//screen with a platform-adaptive transition.
var route = new MaterialPageRoute(
builder: (BuildContext context) =>
new SecondScreen(value: homelist),
);
//A Navigator is a widget that manages a set of child widgets with
//stack discipline.It allows us navigate pages.
Navigator.of(context).push(route);
// }
}, child: Text('Book'),
),
],
),
)
],
),
),
],
),
),
);
}
}
//Future is n object representing a delayed computation.
Future<List<Homes>> downloadJSON() async {
final jsonEndpoint = "https://homeshouse.000webhostapp.com/get.php";
// " 192.168.0.106/";
// final Uri url = Uri.parse(jsonEndpoint);
final response = await get(Uri.parse(jsonEndpoint));
if (response.statusCode == 200) {
// final json = "[" response.body "]";
// List homelist = (jsonDecode(json) as List<dynamic>) ;
List homelist = json.decode(response.body);
return homelist.map((home) => new Homes.fromJson(home)).toList();
} else
throw Exception('We were not able to successfully download the json data.');
}
class SecondScreen extends StatefulWidget {
final Homes value;
SecondScreen({Key? key, required this.value}) : super(key: key);
@override
_SecondScreenState createState() => _SecondScreenState();
}
class _SecondScreenState extends State<SecondScreen> {
@override
Widget build(BuildContext context) {
return new Scaffold(
resizeToAvoidBottomInset: false,
appBar: new AppBar(title: new Text('Detail Page')),
body: new Container(
child: new Center(
child: SingleChildScrollView(
child: Column(
children: <Widget>[
Padding(
child: new Text(
'House DETAILS',
style: new TextStyle(
fontWeight: FontWeight.bold, fontSize: 20.0),
textAlign: TextAlign.center,
),
padding: EdgeInsets.only(bottom: 20.0),
),
Padding(
//`widget` is the current configuration. A State object's configuration
//is the corresponding StatefulWidget instance.
child: Image.network('${widget.value.image_url}'),
padding: EdgeInsets.all(12.0),
),
Padding(
child: new Text(
'NAME : ${widget.value.name}',
style: new TextStyle(fontWeight: FontWeight.bold),
textAlign: TextAlign.left,
),
padding: EdgeInsets.all(20.0),
),
Padding(
child: new Text(
'desciption : ${widget.value.desciption}',
style: new TextStyle(fontWeight: FontWeight.bold),
textAlign: TextAlign.left,
),
padding: EdgeInsets.all(20.0),
)
],
),
),
),
),
);
}
}
class Housedetails extends StatelessWidget {
@override
Widget build(BuildContext context) {
// ignore: unnecessary_new
return new MaterialApp(
debugShowCheckedModeBanner: false,
theme: new ThemeData(
primarySwatch: Colors.deepOrange,
),
// ignore: unnecessary_new
home: new Scaffold(
// drawer: Drawer(child: MainDrawer()),
resizeToAvoidBottomInset: false,
appBar: new AppBar(title: const Text('Popluar Homes')),
// ignore: unnecessary_new
body: new Center(
//FutureBuilder is a widget that builds itself based on the latest snapshot
// of interaction with a Future.
// ignore: unnecessary_new
child: new FutureBuilder<List<Homes>>(
future: downloadJSON(),
//we pass a BuildContext and an AsyncSnapshot object which is an
//Immutable representation of the most recent interaction with
//an asynchronous computation.
builder: (context, snapshot) {
if (snapshot.hasData) {
List<Homes> homelist = snapshot.data;
return new CustomListView(homelist);
} else if (snapshot.hasError) {
return Text('${snapshot.error}');
}
//return a circular progress indicator.
return new CircularProgressIndicator();
},
),
),
),
);
}
}
void main() {
runApp(Housedetails());
}
//end
CodePudding user response：
It's not working anymore because now you have null safety on.
With it, variables cannot be null if they haven't got a ? at the end. For example:
String myString = "Hello World"; //This CANNOT be null
String? myString = null; //This CAN be null
In your code, you will need to check if your List<Homes>? is null before using it.
You can use a null check ! as:
List<Homes>? myOldList = null;
List<Homes> myNewList = myOldList!; //If myOldList is null, an Exception will be thrown.
List<Homes> myNewList = myOldList ?? []; //If myOldList is null, assign an empty list.
Or, in your FutureBuilder you should check if is not null.
if (snapshot.hasData) {
if(snapshot.data != null){
List<Homes> homelist = snapshot.data;
return new CustomListView(homelist);
//.......
CodePudding user response：
The reason for the error you're getting is that you're trying to assign a nullable value to a non-nullable. What you can do here is add null check or utilize the bang (!) operator when assigning the value to determine that the object is indeed non-null.