Rebuild widget when contents of list change - flutter

Question

I have objects in a list that users can remove. If the list is empty, I want to display some text but I tried to do this with a ListView.builder() and it displayed the text many times and I want it to be displayed just once. Is there some sort of property that I can listen to in the list?

Answer 1

import 'package:flutter/material.dart';
main() => runApp(MyApp());
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
List items =new List();
bool _isLoading =false;
#override
void initState() {
// TODO: implement initState
super.initState();
items = getDummyList();
setState(() {
_isLoading=false;
});
}
#override
Widget build(BuildContext context) {
return
MaterialApp(
home: Scaffold(
body: _isLoading
?Center(
child: CircularProgressIndicator())
:
items.length==0?Center(child: Text('No items in the list'),):
Container(
child: ListView.builder(
itemCount: items.length,
itemBuilder: (context, index) {
return Dismissible(
key: Key(items[index]),
onDismissed: (direction) {
setState(() {
items.removeAt(index);
});
},
child: Container(
height: 50.0,
decoration: BoxDecoration(border: Border.all(width: 1.0)),
padding: EdgeInsets.all(5.0),
child: Row(
children: <Widget>[
Text(
items[index],
style: TextStyle(
color: Colors.black,
fontSize: 20.0,
),
)
],
),
),
);
},
)),
),
);
}
List getDummyList(){
setState(() {
_isLoading=true;
});
List list = List.generate(5, (i) {
return "Item ${i +1 }";
});
return list;
}
}
Check out this example , i have made a swipe dismiss example for listview,where if you remove the items it will display the text.
let me know if it works.
Thanks.